Get a spoon.
This sauce from my friend Erin is so good you're going to need one. It's awesome with corned beef & cabbage or with ham.
2 C half and half or milk, heated (not boiled)
4 T butter
4 T flour
2 T yellow mustard (like French's)
4 T horseradish
2 t apple cider vinegar
4 T sugar
Salt and pepper
Melt butter in a sauce pan, then add the flour. Add the half and half. You can also use milk and then just add a couple of tablespoons of half and half for flavor. After the sauce thickens to the consistency of a cream soup, take it off the heat and add the mustard, horseradish, vinegar, and sugar. Also salt and pepper to taste. If you need to warm up the sauce, do it on low heat or it will kill the taste of the horseradish.
The Johnson Family Cookbook