Brush the salmon fillets with 1/2 tbsp soy sauce on all sides. Peel the asparagus and cut off the woody ends. Place the steaming basket on a saucepan filled with water. Place the asparagus and salmon fillets in the steaming basket and steam over a low heat for about 15 minutes.

For the sauce: Bring 1 tablespoon of soy sauce and 1.5 tablespoons of apple balsamic vinegar to the boil in a small saucepan and simmer for about 2 minutes, then stir in the butter in small pieces with a whisk.

Spread the sauce on the plates, top with the asparagus and the salmon fillets, garnish with a little dill and serve.