I think that eating vegetarian is one of the easiest ways to save money and improve your health. I am not strictly vegetarian, but most of my meals do not include meat.
#1. Vegan/Vegetarian norms.
Meat as a main dish or main attractive component of a main dish is normative in America. Many vegetarian dishes fail to please because they are designed and cooked within a meat-normative framework. (or because they are served to someone who dearly holds on to a meat-normative culture.) Vegan norms are "common sense" dishes, cooking memes and strategies that are sometimes not-so-common, and limited to cooking from vegetables, tubers, legumes, seeds, fruits, nuts, grains, and fungi. Someone who has vegan norms can cook a meal that will appeal to a wide range of people, even though it doesn't contain any high-calorie, high-cost crowd pleasers like meat or cheese.
#2. Fried Tofu
Tofu is a strange beast, especially for those unfamiliar with it. It is a wet soy bean curd with lots of good nutrients, and there are lots of different kinds of tofu and lots of different uses for it. My favorite is Extra Firm Tofu for frying.
Price. $1 / wet lb. Your local big box store may sell tofu as a specialty product for 2 or 3x it's actual price. Visit the local Asian grocery for an honest deal.
Usage: Tofu is porous, and it is water-logged when you buy it. Do not treat tofu like meat. You cannot marinate it. You cannot just cook it and expect it to taste ok on its own. For "correct" fried tofu, you have to dry it first. Lay a clean kitchen towel on your countertop. A paper towel will not work, unless you want to repeat this process three times and waste a ton of paper. If you don't have a clean kitchen towel, and you are a bad enough lady or dude, you may use a clean T-shirt instead. Slice your tofu 1cm or thinner, and lay the slices onto the towel, leaving space between slices. Roll the towel and tofu up and press down firmly with your hands. You want to get out as much water as you can. Unfurl the roll and lay the towel out to dry. The tofu should be much less wet. Heat a skillet to high heat (I use cast iron for all my frying, and highly recommend it for cooking tofu. If you have a teflon non-stick pan, do not attempt the following unless you like injecting Flourine gas into your food.) Heat the pan until it is exceedingly hot. Add a considerable amount of high-temperature oil. I use canola oil. I usually heat the pan until it reaches the smoke point of canola oil (400°F for those of you with infrared thermometers). Applying the tofu should cool down the pan. Don't splash hot oil on yourself. You are not deep frying, you just need a bit of oil to compensate for the thirsty dried tofu. At this temperature, you should not have any problems with sticking as long as you give it a minute or two untouched on each side before flipping.
After your tofu is golden brown / brown / black, you are finally ready to flavor it with a sauce. I usually dump out the tofu, slice it this way and that with a 8" chef's knife to get nice trianglular, trapezoidal, and paralellogram-styled pieces, then toss it in a bowl with the sauce of choice before adding to the dish. Buffalo wing sauce works great, peanut sauces work great, adobo sauce works great, really anything you can think of is a valid choice. You can also dump the cooked tofu into your favorite soup / stew.
The fried tofu is still porous, and quite dry, so leaving it in the sauce and letting it sit will allow the sauce to permeate and absorb. You might be surprised how much it can soak up, and that's good for the flavor and texture of the tofu.
#2.5 Dry TVP.
Related to tofu: TVP stands for Textured Vegetable Protein and it is a close relative to Tofu, as it is usually made from soy beans. Usually it comes dry in a bag. It has a tan color.
Price: I was able to find it at my local Mexican grocery store being sold as "Soya" for $3.50 / dry lb. This is a good price, considering that when it is hydrated it will be less than 1$ a pound.
Cooking with TVP is the opposite of tofu, you have to add water to it before cooking, which is nice, because you can add the sauce right away. It will absorb the water and take on a consistency similar to chunks of sausage. I think TVP cooked in saturated fat with the right flavorings could "pass" as pork sausage for most people.
#3 Vegetable soups/stews
A well-executed soup or stew will bring the boys to the yard. It will make your house smell amazing. I am an indian/asian food fanboy, so my favorites tend to be "curry" style stews, hot and sour soups, ramen soups, etc.
I also appreciate simplicity. One of the simplest and most rewarding things you can cook might be thai curry style stew. The key ingredients are:
Unsweetened coconut milk. (Not coconut water, not cerial milk, but actual coconut milk from a can. Look for the imported brands like Chaokoh, Aroy-D, etc. Check the ingredients. You want coconut and water, no other stuff. The more coconut the better. High fat content is a must-have.) About $1.30 / LB.
GOOD curry paste. Skip the American brands like Thai Kitchen. Again, imported is usually better. My favorite is Mae Ploy. Their stuff tastes great, has the right ingredients, and best of all, it's dirt cheap. You can get an entire KILO of the stuff for about 5 to 7 dollars at your local Asian grocery. Now that should last you a while :)
You should start with a large stock pot that can handle acidity (not aluminum or cast iron), then boil water with some tubers or squash cut to 1 inch cubes (potato, sweet potato, yam, butternut etc). You don't want too much water. Just enough to barely cover the tubers. Next, add a deluge of vegetables to the pot. Add those with the highest cook time first. Use whatever you have. In order: Carrots, Cabbage, Onions, Kale, other brassicas like Brocolli / Bok Choi, Eggplant, Bell Pepper, Jalapeño, fresh ginger, fresh garlic, are all fine. Your pot should not have enough water to cover everything. That's fine. Add your can of coconut milk, curry paste to taste, and you should end up with a chunky, stewy mixture. Depending on your curry paste and your taste, you may wish to add additional spices or flavorings. Fish Sauce and Lime Juice are a couple of my favorites.
Add vegetables that are easy to overcook last. Cilantro, Sweet Onion, Spinach, Greens, Tomatoes, etc.
Serve alone, with rice, bread, noodles, whatever.
Ramen and Tom Yum style soups are one of my favorite quick meals. Boil some water, add vegetables, again, longest cook time first, maybe toss in an egg to poach, then add your instant ramen noodles and salt packet or Tom Yum Soup Paste. This is very flexible and you can add just about anything to it.
The most "fancy" ramen I ever made had a spicy Miso paste broth, wheat noodles cooked in basic (sodium carbonate, aka washing soda) water and strained, and topped with blended baked eggplant, fried kale and mushrooms w/ garlic, baked brown sugar sweet potato and salmon with sesame seeds and sweet soy sauce. Storing everything in separate containers + microwaving allowed it to be fresh leftovers for a week. It was fun to make and eat, and everyone at my workplace was jealous :P
#4 Pressure Cooker for Legumes
This may be one of the most "mustacian" kitchen gadgets that one can possess. Why? Because it is a fixed cost investment which generates returns for as long as you use it. A pressure cooker saves you valuable time by cooking tough foods faster. It can beat cheap, tough, and gamey meats into submission and make them melt in your mouth. Best of all, it allows you to buy dried beans and cook them.
Many every-day foods like refried beans, hummus, falafel, red beans and rice, etc, are quite expensive to buy, compared to their raw ingredients. Why? Because processing the raw ingredients (Dry Legumes) into edible food takes a lot of energy and not everyone has the equipment to do it, so they sell the processed stuff in cans and plastic for a high markup. A pressure cooker will open this door and make it easy to turn cheap and nutritious raw dried legumes into delicious food.
Making fresh falafels from dried beans is quite the experience. You will need to cook the chickpeas / garbonzo beans until very soft, then mush them up, add minced onion, garlic, celery, and spices, and fry them in a pan with a considerable amount of oil on high heat. I usually make them flat like pancakes. Serve with a sauce obtained by chucking cucumbers, yogurt, garlic, lemon, olive oil, and salt into a blender.
#5 Fermentation
Fermentation is great for lots of reasons; it gets you drunk, it can provide interesting flavors, consuming active cultures can help your digestive health, and sometimes the cultured yeast/bacteria can even provide additional nutrients that might not have been available in the food in the first place. Also, it makes bread possible. Bread is pretty cool, right?
Saurkraut and Kimchi are a couple of the easiest fermented foods to make. Contrary to what you may expect, making your own sauerkraut and Kimchi is not dangerous, and in fact, it's kind of hard to mess it up if you can do a google search and follow instructions.
First, you will need a watertight pot to ferment your cabbage in. First, the pot must be extremely non-chemically-reactive. Stainless steel might work, but you are better off with ceramic, glass, or HDPE (High Density Poly-Ethylene, or #2 recyclable. This is what food-safe 5 gallon buckets are made out of, which is what I use.) You will also need a "lid" that fits snugly inside the pot, and again, it must not be chemically reactive. Usually a dinner plate works perfectly.
To ferment cabbage into saurkraut, you need to cut it up into very very small pieces or strips first. Like 0.1 to 0.3 cm thick. Salt the cabbage with kosher salt (not iodized as it will kill the bacteria) and firmly pack it into the pot. Add any desired flavorings like garlic, dill, or hot peppers. After packing your cabbage and mixing it, packing and mixing, and packing and mixing, you should notice that the salt has drawn enough water from the cabbage to cover it if you press down. If you don't get enough water, you can add some until the cabbage is covered.. If you live in an area with a very high chlorine concentration in your tap water, then you will need to get distilled water or other water that does not contain tons of chlorine. For me, in Wisconsin, the tap water worked fine.
At this point, you can place your "lid" on top, and then place a heavy weight on top. (I used a cinder block wrapped in a couple garbage bags). Let the cabbage sit like this for a month or two at room temperature. Make sure that the water level is always above the "lid". When it is done fermenting, carefully remove the "lid". There may be some small amount of mold on the surface of the water or on the lid. This is fine, and normal. Just pour it off with the water, and scrape off any kraut where a piece of mold landed on it. After that, you can scoop your kraut into smaller containers and store it in the fridge. You can also can it at high temperature in a Mason Jar and store it on the shelf for years, although doing so will kill the active culture.
For Kimchi, start with Napa Cabbage. You can make your cabbage pieces much larger (1-2 inch), but you must add much more salt and bruise the cabbage a bit, let it sit for about 30 minutes, then rinse much of the salt off before starting the fermentation process. Also, since it is Kimchi, you will add lots of hot peppers, some fish product (fish sauce, shrimp powder or paste, etc), and a bit of ginger and garlic as well. You can also add other kinds of vegetables like Bok Choy, Cucumber, Daikon Radish, Carrot, etc. I usually make my kimchi in a 1-gallon mason jar with the lid loosely-closed instead of the pot and lid method, and it works fine. Kimchi does not need to sit for as long as saurkraut, at least in my opinion. I usually put it in the fridge after a week.