In a large pan, melt the butter over medium-low heat. Add the gnocchi and sauté for 5 minutes. Put the salmon in a large bowl and toss with lemon juice, 5 tablespoons of oil, salt and pepper. Let it rest in the marinade for about 10 minutes per side.
In the meantime, boil the asparagus in a pot with salted water for about 13 minutes, drain and let cool. Cook the fillets of salmon in a pan with 2 tablespoons of oil for about 3 minutes per side and, once ready, serve with asparagus and gnocchi.