In the meantime, heat a griddle pan over a high heat. Once hot, add the burgers and fry for 3-4 minutes on each side until nicely cooked on each side and just cooked through in the middle. If you ...

If using sliced onion, sauté in some duck fat (or a fat you prefer) and season with salt and pepper to taste. You can do this in the same skillet you’re cooking the burgers in, then set aside.