Ketchup, mustard, relish, sliced pickles
Lettuce, tomato slices
4 soft hamburger buns, lightly toasted
4 - 8 slices cheese of choice, I use Swiss (optional)
2 tbsp. oil
3 onions, peeled and sliced into rings
Salt and pepper
800g - 1kg / 1.6 - 2 lb ground beef (mince), 20%+ fat