Indian curries made with chickpeas and a ton of vegetables are hearty and flavorful. I make a vegetable korma that uses frozen vegetables, canned chickpeas, canned coconut milk, canned tomato. We keep the ingredients on hand and it's fast and tasty, plus you can use any fresh vegetables you have. If you have more time, soak dry chickpeas yourself. The coconut milk makes it very satisfying, and it's even vegan.
Chili and spaghetti lend themselves well to either going fully vegetarian or just stretching out the meat with beans or diced zucchini/yellow squash. I make a black bean mix (black beans, chili powder, garlic, onion, salsa, corn) that is also really fast and easy and filling. This is a weekly dish for us, and we either make it into burritos or serve it over rice. Again, it can be done with dry beans and fresh corn, or it can be entirely cans/frozen, and it's vegan. Egg based dishes are also really satisfying. Sometimes in the morning, I'll heat and mash a little of the black bean mix and plop a fried egg on it. We also use the black bean leftovers dolloped into quesadillas.
I do a lot of pureed vegetable soups - saute onion and garlic in some oil, throw in all the random vegetables you have, top it up with broth, and cook until soft. Puree it quickly, salt and pepper, then serve with a small pat of butter or splash of cream, and you can sprinkle grated sharp cheese on top. Do garlic bread, crackers, or cheese toast/grilled cheese on the side. You can seriously use anything, including stem pieces and beans. I do a homemade broccoli cheddar soup like this. Last night I made one with cauliflower, radish leaves, carrots, celery, and green onions that were all wilting on me.
We eat a ton of meat too, but I usually do a few vegetarian dishes a week.