01 - Heat olive oil in a skillet over medium heat. Add onions and cook until softened, about 2 minutes. Add garlic and sauté for 30 seconds until fragrant.
02 - Add ground beef to the skillet and cook, breaking it up with a spoon, until browned, about 5 minutes. Stir in taco seasoning, salt, pepper, tomato paste, and water. Simmer for 2–3 minutes until the sauce thickens. Remove from heat.
03 - Heat tortillas in a dry skillet or microwave until pliable and easy to fold without cracking.
04 - Lay each tortilla flat on a surface. In the center, layer equal portions of rice, beef mixture, black beans, diced tomato, salsa, sour cream, and a mix of both cheeses. Sprinkle with cilantro if desired.
05 - Fold in the sides of each tortilla, then roll up tightly from the bottom to form secure burritos, ensuring all fillings are enclosed.
06 - Spread a thin, even layer of softened butter on the outside of each burrito to promote golden crisping.
07 - Heat a large skillet or griddle over medium heat. Place burritos seam-side down and grill for 2–3 minutes per side, pressing gently with a spatula, until tortillas are golden brown and cheese is melted throughout.
08 - Slice each burrito in half diagonally and serve immediately while hot and crispy.