In a medium saucepan, heat the oil over medium-high heat until hot. Add the chopped onion and bell pepper and cook until the vegetables are soft, about 4 minutes. Add the garlic, salt, cumin, and oregano, and cook for 1 minute, stirring constantly. Add the rice and cook, stirring, until fragrant, about 2 minutes.

Add the water and drained beans and bring to a boil. Stir well, reduce the heat to low, and cover the saucepan. Cook for 20 minutes, undisturbed, until the rice is tender and has absorbed all of the liquid. Remove from the heat and let stand, undisturbed, for 5 minutes before serving.

Heat the flour tortillas according to package directions -- the microwave works well for this if you have one available.

Fill each warm tortilla with a heaping 1/3 cup of the cooked rice and bean mixture placed in a line down the center of each tortilla. Top each mound of rice with 2 tablespoons of the grated cheese and roll the bottom side of the tortilla over the filling. Fold both of the side edges up over the filling, then roll the tortilla to form a cylinder shape.

Spoon 3 tablespoons of salsa over the top of each burrito and then top each with 2 tablespoons of the sour cream. Garnish each burrito with 1/2 tablespoon of chopped cilantro and serve with hot sauce and avocados, if desired.