Find a fish, either from the store or the sea.
Stuff the belly of each trout with some rosemary and season with salt and pepper. Rub some oil over the skin of the fish.
Place the trout over indirect heat and grill, flipping once, until cooked through, 20 to 40 minutes, depending on the size of the fish and the temperature of your grill. The fish is done when it has those lovely grill marks on the outside and the fish flakes easily when you gently tug at the inside with a fork.
During the last few minutes of grilling, toss the lemon slices on the grill to warm and turn occasionally so they don’t scorch.
Serve right away together with your favourite side dish.