Pat the skin of the salmon fillets dry with paper towel and then sprinkle the skin with a little sea salt.
Heat a large, non-stick frying pan over medium-high heat. Add the salmon, skin side down and cook for 4 to 5 minutes or until skin is crisp.
Season with a little sea salt and freshly ground white pepper, turn and cook, covered for another 2 to 3 minutes for medium or until cooked to your liking.
Melt the butter in small saucepan and saute the spring onion for 2 minutes, until it is soft.
Stir in the wine/vermouth, bring to the boil and boil rapidly for 30 seconds.
Serve with steamed asparagus or dressed salad leaves and a crisp potato stack.
You can buy horseradish mustard, alternatively a nice grainy mustard would work well.
I make my own horseradish mustard.