Heat a large skillet over medium heat. Add ground beef and diced onion. Cook for 7 to 8 minutes, breaking up the meat, until fully browned and the onion is tender.

Drain excess grease from the pan. Stir in minced garlic, taco seasoning, and salsa. Simmer for 3 to 4 minutes until the filling is thick and fragrant. If it looks too wet, cook for one more minute.

Lay tortillas flat on a clean surface. Spread a spoonful of refried beans down the center of each tortilla.

Add a scoop of the beef mixture over the beans. Sprinkle a generous amount of shredded cheese on top. Do not overload the tortilla or it will be hard to roll.

Fold in both sides of the tortilla, then roll firmly from the bottom up. Press the seam down to seal.

Oven method: Preheat oven to 400 degrees F (200 degrees C). Place chimichangas seam-side down on a baking sheet, brush with oil, and bake 18 to 20 minutes, flipping once halfway through, until golden and crispy. Skillet method: Heat 2 to 3 tbsp oil over medium heat. Cook seam-side down for 2 to 3 minutes per side until deep golden brown.

Remove from heat. Let rest 2 minutes before serving. Top with sour cream, guacamole, lettuce, or salsa as desired.