Let's Eat Plants has a burrito recipe in the video Genius Hack to Eat Healthy for $5/Day. She starts on the burrito at around the 2:15 mark.
Ingredients
75g (uncooked) black beans $0.15 (I cooked 300g in total for 4 servings, and still had some leftover)
1 tsp. chili powder $0.02 (I recommend adding a pinch of salt here as well)
40g (uncooked) rice $0.09 (I cooked 250g in total for 4 servings, but had so much leftover, I've reduced the per serving amount to 40g uncooked (160g uncooked for 4 servings))
50g frozen veggies $0.17 (I cooked 200g in total for 4 servings but had a lot leftover with the rice)
1/2 cup salsa $0.14
Tortilla $0.39
Total cost per serving = $0.95
Optional: add onion, cilantro, jalapeƱos, extra spices, salsa or hot sauce