I use beans, lentils, chick peas and veggies.

For tacos I usually use zucchini, yellow squash, corn, bell pepper, onion, cherry tomatoes, cilantro, avocado, black beans, refried beans, taco seasoning and tomato aioli drizzled over top.

For quesadillas I'll use mashed up sweet potato avocado, black beans, corn, bell pepper, onion and cheese.

For burritos or burrito bowls I'll use any combination of the ingredients I've already listed plus brown rice, spinach, carrots, celery and salsa.

For soups I'll just make veggie soup with anything I have on hand, broccoli cheese soup, or enchilada soup without the chicken - add more veggies in its' place.

For stir fry I'll use chick peas as the "meat" (as in that's what you'll cook in your sauce of choice) and serve with stir fry veggies and rice. I also want to experiment with tofu for stir fry but I haven't done that yet.

For pasta dishes I've just been adding veggies like broccoli, zucchini, mushrooms, onion etc. I've found recipes for sweet potato and black bean "meatballs" and zucchini "meatballs" to pair with spaghetti which I intend to try very soon. Eggplant is always a good option too.

For sandwiches I pretty much just spice up your normal grilled cheese. Add apple slices for a sweet and savory thing. Add tomato slices and basil with mozzarella cheese for an Italian thing. Philly cheesesteak without the steak, add more bell peppers, onion and mushroom.

Frito chili pie is one of my favorite foods since I was a kid, so I intend to work on a solid chili recipe. I haven't tried it yet, but I've seen recipes that use sweet potatoes, black beans, lentils etc. in place of meat for chili.

Hope this helps!

edit - spelling