@whitesand - The mustard sauce is actually chilled then served on the side either as a spread or a dipping sauce. To answer your question, yes I think it would taste wonderful with grilled or smoked salmon.
The ingredients I used for the mustard sauce were: one teaspoon spicy Dijon mustard, two tablespoons honey mustard, one and one half tablespoons of white-wine vinegar, about one half cup of fresh chopped dill, three quarters cup cooking oil, two teaspoons of sugar, salt and pepper to taste and about a tablespoon of cold strong black coffee.
I mixed all the ingredients together in the blender, except the dill and salt and pepper which I stirred in last in a bowl that I transferred to the refrigerator for about four hours. This step is important to allow the flavor to intensify.
I hope your family enjoys it and I do hope you try the gravlax salmon recipe sometime too. It's really quite delicious. The next salt water fish I'll be experimenting with is mahi mahi of the pacific.