Heat the 1 tbsp olive oil in a medium saucepan over medium heat. Toast the 1 cup rice for 2 minutes, then add 2 cups water, 1 tsp cumin, 1/2 tsp garlic powder, and 1/2 tsp salt. Bring to a boil, cover, reduce to low, and cook for 18 minutes. Rest off-heat for 5 minutes, then fluff.

Warm the 16 oz refried beans in a small saucepan over medium-low heat for 4 to 5 minutes, stirring frequently, until hot and spreadable.

Warm each flour tortilla in a dry skillet over medium heat for 20 to 30 seconds per side. Stack under a kitchen towel to keep pliable.

Lay 1 tortilla flat. Layer 1/4 of the beans, 1/4 of the rice, 2 tbsp sour cream, 1/4 cup guacamole, 1/4 cup cheese, 1/4 cup lettuce, and 1/4 cup diced tomato in the center, leaving a 2-inch border. Fold the sides in and roll tightly from the bottom. Repeat with remaining tortillas.

Place each burrito seam-side down, slice in half on a diagonal, and serve cut-side up so the layers are visible.