Sauté the onion in olive oil until softened and let cool.
Mix beef mince, chillies, parsley, salt, pepper, and onion in a bowl.
Form four burgers, wrapping the meat around a piece of cheese so it is fully enclosed.
Cook burgers on a hot griddle pan for 4 to 6 minutes per side.
Toast the burger buns cut side-down on the griddle for one minute.
Heat vegetable oil in a deep pan for frying.
Fry potato strips in batches for 3 to 4 minutes until golden and drain on paper.
Boil corn on the cobs in salted water for 7 to 8 minutes.
Slice kernels off the cooled corn cobs into a bowl.
Mix corn with butter, chilli, and lime juice, then season.
Assemble buns with lettuce, tomato, and the cooked burger patty.
Serve burgers alongside the fries and sweetcorn relish.