Lay out two large sheets of heavy-duty aluminum foil (about 12x18 inches each). Lightly grease the center with a bit of butter or nonstick spray.
Place one salmon fillet in the center of each foil sheet. Season with salt and pepper. Top each fillet with 1 tablespoon butter, 2 lemon slices, and 2 sprigs of dill. If using, drizzle 1 tablespoon of wine or broth over each.
Fold the foil up and over the salmon, crimping the edges tightly to create a sealed packet. Leave a little air space inside for steam to circulate.
Preheat your campfire to medium heat (coals should be glowing, not flaming) or set up a camp stove with a grate. Place the foil packets directly on the coals or on the grate.
Cook for 10-15 minutes, flipping once halfway through if on coals. Check for doneness by carefully opening a packet: the salmon should flake easily with a fork and be opaque throughout. Internal temperature should reach 125-135°F.
Carefully open the packets (watch for hot steam) and serve immediately. Squeeze extra lemon over the top if desired.