Mix minced meat with grated onion, chopped parsley, finely chopped jalapeno peppers with seeds, sea salt, finely chopped garlic, and freshly ground pepper in a bowl. Knead until well combined. Divide into 4 equal portions and shape each into a patty approximately 3 cm thick.
Preheat grill to high heat. Toast burger buns on the grill for 1-2 minutes per side until lightly browned, then set aside.
Place patties on the grill and cook over high, direct heat for 5-6 minutes with the lid closed.
Flip the patties and cook for 4-5 minutes. Then place a cheese slice on top of each patty, close the lid, and cook for 1-2 minutes until the cheese melts. The patties should reach an internal temperature of 71°C (160°F) for safe consumption of ground beef.
Remove patties from grill. Place each patty on a toasted bun, top with a lettuce leaf, and serve immediately.