Light a campfire or fire bowl, without using any firelighters or extra fire starters.
Season salmon filets generously with sea salt and black pepper. Spread 1 tablespoon mustard on top of each salmon filet.
Layer 2 lemon slices, 1 sprig of tarragon, 1 sprig of dill, a few slices of shallot, 1 tablespoon butter, and some garlic on each salmon filet. Splash some olive oil over the top.
Wrap salmon filets individually in aluminum foil. Make the sure the foil is sealed well.
Put the foil-wrapped salmon directly in your campfire. Cook for 6-8 minutes, until the fish is cooked to your liking.