After 6 years of living alone, and turning vegan the last 10 months, I've got this dialed down to a science and never throw out food:
-Buy a Joyce Chen carbon steel wok and learn to love stir frying. Takes a few minutes and you never need to have leftovers because you only have to cook for one plate at a time.
-Get a rice cooker and cook like 4 or 5 cups per batch. Whatever i don't use for the meal on hand, I separate into small single-serving Pyrex bowls in the fridge and they last like a week. I'll either stir fry them or microwave them as needed.
-Get a vitamix if you can swing it. Just bought one to replace my ninja blender and holy crap is it awesome.
-I can buy bags of dried beans, rice, oatmeal, raisins, peanut butter, bananas, tomatoes, chocolate cashew milk, frozen berries, and salsa/tomato sauce in bulk. They never expire before I get to them. If the bananas start to go brown, just peel them and freeze them in a ziploc bag. Then when you get a sweet tooth, throw a couple in the vitamix with some chocolate cashew milk (not too much or you get a smoothie), and boom, chocolate banana ice cream. Top with peanut butter.
Get those large bags of mixed vegetables that are already cut (corn,carrots, green beans) for 5 or 6 bucks. Get the wok smoking hot and pour in as much veg as you want to eat straight from the frozen bag, heats up in a few minutes. Also buy those bags of kale or spinach and throw them in the wok around the halfway mark. They taste way better cooked if you aren't a fan of them raw. My go to meal is a big steel mixing bowl of some combination of stir fried veg, beans, rice, spinache/kale, salsa, mayo (the Just Mayo brand is vegan and delicious. Costs the same as regular mayo and just a spoonful adds a nice little zing to the taste. Don't knock it till you try it). Or go with soy sauce for Asian flavor (put the soy sauce in the wok of veg/rice in the last minute or so).
My go-to vitamix shake is kale/spinach, frozen berries, fresh/frozen banana, chocolate cashew milk. If your lettuce starts to go bad in the fridge you can freeze it and use it for smoothies.
Oatmeal breakfast: Put oatmeal, raisins, fresh banana, scoop of peanut butter, and enough chocolate cashew milk to coat all the oatmeal in a large bowl and stir. I think it tastes better than warm oatmeal.
I also make my own hummus: Can of chick peas (drain and fill like a 1/4 of the can with water, spoonful of diced garlic (or 1 clove or garlic powder), spoonful of tahini (optional), salt, pepper, bit of lemon juice, splash of olive oil, some roasted red peppers (optional), and blend. Add water if you need a more thin consistency.
The goal is to stick with things that have a huge shelf life or can be frozen at the end of their fresh life and re-purposed.
Pro tip: If you're an avocado freak like me, buy them when they are still green and hard as a rock and put them in the fridge. It extends their lifespan over several days instead of 1 or 2.