Saute the diced onion and carrot in a tablespoon of olive oil until the onion is translucent. Then, take the vegetable mixture and put it in the blender, adding the can of black beans after straining half of the liquid. Add salt, pepper, and cumin to the mixture to taste and blend until it is the consistency of refried beans. Warm the beans in a skillet. In a small bowl, combine sour cream with a bit of cumin for flavor (you can also use taco seasoning).
In a pan coated with olive oil (you can also use butter), saute the tortillas until they brown a bit on the edges.
Then, smear some of the black-bean mixture in the center of each tortilla, roll them up, top with seasoned sour cream and serve.
Green onions, salsa, and guacamole are also great garnishes.