2 tablespoons yellow mustard seeds
4 medium shallots, peeled and thinly sliced
2/3 cup sherry vinegar
1/2 cup heavy cream
1/2 cup unsalted butter, softened
1/4 cup whole-grain mustard
Salt and freshly ground pepper, to taste
2 to 4 pounds fresh green beans (preferably haricots verts), trimmed

In a dry skillet, over high heat, toast the mustard seeds until they begin to pop and brown, about 1 minute. In a large, heavy skillet place the shallots, vinegar and 1/4 cup water and simmer over low heat until liquid is reduced to about 1 tablespoon, about 12 minutes. Add the cream and simmer over moderate heat until thickened, about 5 minutes. Transfer to a bowl and let cool to room temperature, then stir in the butter, prepared mustard and toasted seeds. Season with the salt and pepper. This makes enough for 4 pounds of beans, so reserve what you don't need. May make butter 2 to 3 days in advance and refrigerate, covered, until ready to use.

In a large pot of boiling, salted water, cook the green beans until crisp-tender, about 8 minutes at boil point. Place in a serving bowl and add mustard-butter mixture. Serve immediately.

Makes 8 servings.

— Recipe courtesy of The Willows Cooking School.