Mix the burger ingredients together in a bowl and divide and roll into 8 equal size balls, then press to form thin burgers.
Mix the sauce ingredients together in a small bowl.
Heat a little oil in a heavy frying pan, once smoking hot, add the burgers, and use a spatula to press down. Cook for a minute or two until it forms a golden crust.
Carefully flip the burgers, ensuring that you scrape up the crust from the pan. Lay the cheese slices on top of the burgers and cook for 2 minutes until the burgers are just cooked but still juicy and the cheese begins to melt.
Meanwhile, toast the burger bun halves on both sides.
To serve:
Spread burger sauce over the base of each bun and layer with salad leaves, tomatoes, gherkins, cheese-topped burgers and more sauce.