1. Combine the sweetcorn kernels, diced tomatoes and the rest of the ingredients. Cover and refrigerate the salsa for at least 15 min. Season to taste.
2. Heat up a grill pan nice and hot. Combine the minced meat with the cheese and salt. Form the meat into 12 mini-patties (5-6 cm in diameter) and grill for approx. 2 minutes on each side.
3. Slice open the buns and place cut-side up on a parchment-lined baking sheet. Place a grilled patty on each top bun. Toast the buns and patties in the oven on the top rack.
4. Remove the skin and stones from the avocado and mash it with lime juice. Place a spoonful of mashed avocado on each toasted bottom bun. Layer lettuce, coriander leaves and a little salsa on top, then top with the burger patty and the top bun.
5. Serve immediately with the rest of the sweetcorn salsa.