Put all ingredients into a large mixing bowl.
Combine the mixture well with your hands, then divide it into equal portions. Shape these into balls then flatten them between your palms. Put the patties onto a plate and chill for 30 minutes.
Preheat your BBQ, grill or griddle pan. Lightly brush both sides of the burgers with some oil. Barbecue or fry for 4-8 minutes on each side, according to your liking.
If you want cheese on your burger, put a slice on the top after you've turned them over - for the last 3-4 minutes or so.
Meanwhile, cut the buns in half and toast them, cut-side down, on the barbecue or grill.
Assemble the burgers to your liking: layer lettuce, grilled pepper, sliced tomatoes, onion, gherkin and tomato ketchup/mayo on the bottom half of the bun, place the burger on top then cover with the other half of the bun.
Serve with fries on the side.