Step 1: Heat olive oil in a large skillet over medium heat. Add diced onion and cook until softened, about 5 minutes.
Step 2: Add ground beef to the skillet and cook, breaking it up with a spoon, until browned and cooked through, about 8-10 minutes.
Step 3: Stir in minced garlic, chili powder, cumin, smoked paprika, oregano, salt, and black pepper. Cook for 1-2 minutes until fragrant.
Step 4: Add cooked rice and black beans to the skillet, stirring to combine. Cook for 3-4 minutes until heated through, then remove from heat.
Step 5: Warm tortillas in a dry skillet or microwave for 20-30 seconds until pliable.
Step 6: Place a tortilla on a flat surface. Spoon one-quarter of the beef mixture onto the center, leaving a 2-inch border around the edges.
Step 7: Top with shredded cheese, sour cream, salsa, lettuce, tomatoes, and cilantro as desired.
Step 8: Fold the sides of the tortilla over the filling, then roll from the bottom up tightly to form a burrito.
Step 9: Repeat with remaining tortillas and filling. Serve immediately or wrap in foil to keep warm.