In a large nonstick skillet coated with cooking spray, sauté onion and garlic in oil for 2 minutes. Stir in the carrot, chili powder and cumin; cook 2 minutes longer or until carrot is tender. Remove from the heat; set aside.
In a large bowl, mash the pinto beans and black beans. Stir in the oats. Add the mustard, soy sauce, ketchup, pepper and carrot mixture; mix well. Shape into eight 3-1/2-in. patties.
Coat a grill rack with cooking spray before starting the grill. Grill patties, covered, over medium heat for 4-5 minutes on each side or until heated through. Serve on buns with lettuce and salsa. Yield: 8 servings.