Beans, of course!
1 can of black beans
1 packet taco seasoning (watch for milk ingredients in most brands)
1 tomato, chopped (optional)
Partially drain black beans (we don't want this super runny). Pour into frying pan. Add taco seasoning. Stir and heat for 10 minutes on medium heat. Tear or cut iceberg lettuce into small pieces.
Spoon beans into taco shells. Sprinkle with lettuce and tomatoes. Drizzle with taco sauce. That's it! Recipe will make approx 6 tacos.
It's amazingly simple, but equally yummy. Not to mention, packed full of fiber and protein. (Though the pictures shown involve hard shell; this works equally well for soft shell.)