Preheat griddle over medium-high heat. Season burger patties with salt and pepper. Press burgers firmly onto griddle with the back of a spatula to ensure a good sear. Let cook for 2-3 minutes, or until a nice crust has formed. Flip burgers, then add cheese curds to the grill in clusters about the size of the burgers. Let curds cook 30-45 seconds. Flip cheese curds onto the burger patty and remove from the grddle. Turn heat off on the griddle, then toast buns on it for 30-45 seconds. Top buns with lettuce, tomato, mustard and burger, then serve.