Place your salmon on a large sheet of aluminum foil. Sprinkle with salt and pepper. Place a second piece of aluminum foil on top of salmon and fold up all edges to completely seal the salmon. Grill or bake at 350 degrees for 30 minutes. While the salmon is cooking, make the brown sugar glaze by combining the butter, brown sugar and lemon juice. Slice open the foil pack and baste with all of the brown sugar glaze. Let cook for about 5-10 minutes more until glaze is bubbly and syrupy.