Slice the tomato and onion into rings, and the gherkin lengthwise into thin slices.
Heat the oil in the frying pan, then fry the burgers. Fry for 4–5 minutes on each side, flipping occasionally.
Slice the buns in half and spread the mayonnaise on the bottom half. Place the burgers over the mayonnaise and layer the rest of the toppings – cheese, tomatoes, gherkins, onion, and lettuce.
Add a bit of ketchup on top of the lettuce and some mayo, then put the top half of the bun on top.
