Cook the Filling: Heat oil in a skillet over medium-high heat. Add onion and cook until softened, about 3 minutes. Add garlic and bell peppers; cook 1–2 minutes.
Brown the Beef: Add ground beef, breaking it apart. Cook until browned, 5–6 minutes. Drain excess fat.
Season and Simmer: Stir in tomato paste and cook 1 minute. Add cumin, chili powder, paprika, coriander, oregano, cayenne (if using), salt, and pepper. Pour in beef broth, reduce heat, and simmer 5 minutes until slightly thickened. Let cool slightly.
Prepare the Cheese: Combine cheddar, Monterey Jack, and queso fresco in a bowl.
Assemble Chimichangas: Lay out a tortilla and spread a thin layer of sour cream. Spoon about ½ cup beef mixture, sprinkle cheese, and add cilantro if desired. Fold sides in and roll tightly. Secure with a toothpick.
Cook the Chimichangas:
