Preheat the oven to 375°F (190°C) and grease a 9" x 13" casserole dish.
Spread 1/2 cup of enchilada sauce on the bottom of the casserole dish.
In a skillet over medium heat, add olive oil and diced red onion and bell pepper. Cook until the vegetables are tender and lightly browned.
Add the shredded brisket to the skillet and stir to combine with the vegetables. Season with salt and black pepper to taste.
Warm the flour tortillas in the microwave for 10-15 seconds or until they are pliable.
Spread a spoonful of refried beans on each tortilla, leaving a border around the edges.
Add a spoonful of cooked rice on top of the refried beans.
Spoon the brisket mixture over the rice and top with shredded cheese.
Roll the tortillas tightly and place them seam-side down in the casserole dish.
Pour the remaining enchilada sauce over the burritos, making sure to cover them completely.
Sprinkle the top with the remaining shredded cheese.
Bake for 20-25 minutes, or until the cheese is melted and bubbly.
Remove from the oven and garnish with chopped green onion or cilantro.