Heat a large skillet over medium. Add the ground beef and diced onion. Cook, breaking the meat up with a spoon, until the beef is browned and the onion is tender, about 6–8 minutes.

Drain excess grease. Return the skillet to the heat. Stir in the minced garlic, taco seasoning, and salsa. Simmer for 3–4 minutes until the mixture is well combined and slightly thickened. Taste and adjust seasoning. Remove from heat.

Lay a tortilla flat. Spread about 2 tablespoons of refried beans down the center. Top with a generous scoop (about ¼–1/3 cup) of the beef mixture. Sprinkle with a handful of shredded cheese. Fold the short sides in, then roll tightly from one end to the other so the seam is on the bottom. Repeat with remaining tortillas.

Oven method (healthier): Preheat the oven to 400°F (200°C). Place chimichangas seam-side down on a baking sheet lined with parchment. Brush each lightly with vegetable oil. Bake for 18–20 minutes, flipping once halfway through, until golden and crispy.

Skillet method (crispier): Pour 2–3 tablespoons of vegetable oil into a large skillet and heat over medium. Add chimichangas seam-side down. Cook 2–3 minutes per side, turning carefully, until all sides are deep golden and crisp. Transfer to a paper-towel-lined plate to drain briefly.

Let chimichangas rest for 2 minutes before serving. Top with sour cream, guacamole, shredded lettuce, extra salsa, or chopped cilantro as desired.