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.
Spread burger sauce over the base of each bun and layer with salad leaves, tomatoes, gherkins, cheese-topped burgers and more sauce.