Drain and rinse kidney beans. Toss one can of beans into a food processor; pulse to puree. Finely chop onion, grate carrot, and slice bell peppers; set aside separately.
Heat olive oil in a large skillet over medium. Add onions, salt, and black pepper and cook for 5 minutes, stirring occasionally.
Add carrots, chili powder, and oregano; mix well. Cook for 1-2 minutes then stir in the tomatoes; bring to a boil.
Reduce heat to low, cook for 10 minutes. Stir in the the bean puree as well as the remaining can of beans, and cook until heated through.
Serve on whole wheat buns alongside blueberries and bell pepper slices with ranch for dipping.