In a large skillet over medium heat, brown the ground beef along with the finely diced onion for about 5-7 minutes, stirring frequently until the beef is no longer pink. Drain excess grease, then add the minced garlic, taco seasoning, and salsa. Stir and simmer for another 2-3 minutes until heated through.

Warm the flour tortillas in the microwave for about 30 seconds to make them pliable. On each tortilla, spread a layer of refried beans, followed by a scoop of the beef mixture and a handful of shredded cheese. Fold in the sides and roll the tortilla tightly, securing the filling.

For frying, heat about 1 inch of vegetable oil in a deep pan to 350°F. Place each chimichanga seam-side down and fry for 2-3 minutes until golden brown, then flip.

For baking, preheat the oven to 400°F, brush each chimichanga lightly with oil, and bake on a greased baking sheet for 20-25 minutes until golden and crispy.

Once golden and crispy, remove from the oil or oven and allow to cool slightly. Serve hot garnished with sour cream, guacamole, or pico de gallo.