In a small sauté pan over medium heat, combine lemon juice, olive oil, butter, mustard, garlic, cayenne pepper, salt, basil and dill. While stirring, bring to a boil. Reduce heat and simmer for 5 minutes.
While the sauce is still hot, brush on fish. Place salmon fillets onto individual pieces of foil with edges turned up to make a pan. Pour remaining sauce evenly over fish.
Fold foil over create packets. Bake in 350 degree oven for 20 minutes.