I cooked this salmon in an outboard engine on a boat. I was lucky. The heat generated during our short trip was just enough to cook the fish. It was fun, but all in all I recommend using an oven.
Preheat the oven to 210°F (100°C).
Make four double-layered squares of aluminum foil or parchment paper, measuring approximately 12×12 inches (30×30 cm) each. Place one salmon slice in the middle of each. Add one slice of lemon to each slice. Add parsley, capers, salt and pepper. Add butter. Close the foil tightly to retain the evaporating juices.
Bake in the oven for 15-20 minutes until cooked through. The exact length of time depends on how thick your slices of salmon are and how hot your oven is. The fish is ready when it flakes easily when poked with a fork.