1. In a bowl, mix together grated onion and ground beef, season with salt and pepper.
2. Using a fork, spread about 2 tablespoons of beef mixture on one side of the raw tortilla, leaving some space at the edges.
3. Fold the other half over, covering the filling. Gently press on the filling, using the palm of your hand, to remove air pockets. Crimp the edges with the tines of a fork, on both sides (use a different fork, not the one you used for filling). You can also add another layer of sealing by pinching edges with your fingers.
4. For a healthier version, air fry in batches in a basket of your Cuisinart Toaster Oven at 320F (160С) for 5 minutes (until nice golden-brown), then turn and air fry for another 3 minutes. My oven tends to run hot, but you may need to adjust time/temperature.
If you don’t have an air fryer, heat oil in a large skillet over medium heat, enough to cover half of a cheburek. Fry chebureki in batches over low-medium heat, about 4-5 minutes per side. The temperature of the meat filling should be at least 160F (71С).