In a bowl, combine the cooked and shredded beef, shredded cheese, refried beans, diced onion, garlic powder, cumin, and salt and pepper. Mix everything well until you have a thoroughly combined filling.

Lay out a large tortilla on a clean surface. Place a generous amount of the beef mixture in the center. Fold in the sides and roll it up tightly to form a chimichanga.

In your skillet, heat oil over medium heat, enough to cover the chimichangas halfway.

Carefully place the rolled chimichangas into the hot oil one at a time. Fry them until they are golden brown and crispy on all sides, using tongs to turn them for even cooking.

Once crispy, remove the chimichangas from the oil and place them on a plate lined with paper towels to drain the excess oil. Serve hot with optional sour cream and salsa.