In a small saucepan, bring water to a boil. Add rice. Return to a boil. Reduce heat; cover and simmer for 5 minutes. Remove from the heat. Let stand until water is absorbed, about 5 minutes. , Meanwhile, in a large skillet, saute green pepper and onion in oil until tender, 3-4 minutes. Add garlic; cook 1 minute longer. Stir in the chili powder, cumin and pepper flakes until combined. Add beans and rice; cook and stir until heated through, 4-6 minutes. Stir in salsa and remove from heat., Spoon about 1/2 cup of filling off-center on each tortilla. Fold sides and ends over filling and roll up. Serve with cheese and sour cream if desired.