Preheat a griddle or skillet over high heat for at least 5 minutes – with some olive oil.
Divide the ground beef into 6 equal portions and shape them into balls. Should make 6 patties.
Place each ball on the hot griddle or skillet and immediately smash it down with a spatula to form a thin patty. Press down firmly to ensure that the patty is thin and has good contact with the cooking surface.
Season each patty with salt and pepper.
Cook the patties for 2-5 minutes on each side or until they are browned and crispy.
If you're adding cheese to your burgers, place a slice on top of each patty during the last 30 seconds of cooking to allow it to melt.
Caramelize the onion in a separate non-stick skillet until golden brown.
Crack the eggs sunny side up for 2-3 minutes.
Toast the low-carb hamburger buns on the griddle.
Once the patties are cooked to your liking, remove them from the griddle or skillet and let them rest for a few minutes before serving.
Assemble the burgers with a tablespoon of the sauce, 1 slice of tomato, 2 patties each (with a slice of cheese on each patty).
Add the caramelized onions.
Top of the fried egg.
Place the top half of the low-carb bun over the egg and secure with a wooden skewer.