Heat the wine with the tablespoon of sugar until it has reduced by half.
In a frying pan, braise the cleaned morels in the knob of butter, add the sherry carefully so it doesn’t flambé, and leave to reduce. Add the beef stock and the red wine reduction and leave to thicken. Keep aside.
In a blender, mix the foam ingredients until they emulsify and form a truffle foam. Keep it in this state until it is time to serve.
Cut the black cod into 4 pieces, 3 cm wide by 7-8 cm long. Sear on each side in a frying pan with a pinch of salt and a drop of olive oil.
While the black cod is cooking, blanch the asparagus in boiling water for 30 seconds to 1 minute depending on their thickness, and then chill immediately in iced water and drain. Sauté in a frying pan with a drop of olive oil and salt.
Arrange the black cod with the braised morels and sautéed asparagus and top with a spoonful of truffle foam.