Preheat your oven to 400°F. If available, use the convection setting for extra crispiness. Line two large baking sheets with parchment paper and set aside.

In a large bowl, combine the ground beef, grated onion, undrained diced green chilies, chili powder, ground cumin, garlic powder, and kosher salt. Mix thoroughly with your hands until all ingredients are evenly distributed, being careful not to overmix.

Take one flour tortilla and spread about 1 tablespoon of refried beans over one half. Spoon approximately 3 tablespoons of the seasoned meat mixture onto the same half. Sprinkle with 1 tablespoon of shredded cheddar cheese.

Fold the tortilla over the filling and gently press down to keep it closed. Place the assembled taco seam-side down on one of the prepared baking sheets. Repeat with the remaining tortillas and filling, arranging 6 tacos per sheet.

Lightly brush both sides of each taco with neutral oil. This step is crucial for achieving a golden, crispy exterior.

Bake in the preheated oven for 25-35 minutes, flipping the tacos halfway through. The tacos are done when the beef is cooked through (internal temperature 160°F), the tortillas are browned with crisp edges, and the cheese is melted and bubbly.

Remove from the oven and let cool for a minute or two before serving. Serve immediately with your desired garnishes like sour cream, salsa, or shredded lettuce.