Baked Ham with Cucumber, Tarragon, and Mushroom Sauce

1 Tbsp. unsalted butter
4 large mushrooms, sliced thinly
1 cucumber, peeled, seeded and sliced thin crosswise (1 1/2 cups)
2 tsp. finely chopped fresh tarragon + sprigs for garnish
2 Tbsp. heavy cream
1/4 tsp. Dijon-style mustard
3/4 lb. ham steak, trimmed

In a skillet, melt butter over moderate heat until foam subsides. In it cook mushrooms, stirring, until they begin to give off their liquid. Add cucumbers and cook, stirring, 3-5 minutes, or until cucumber is slightly softened. Stir in chopped tarragon, cream, and mustard, and cook until thickened slightly. Put ham in a baking dish and spread with cucumber mixture. Bake in the middle of a preheated 350-degree oven for 10 minutes, or until heated through. Garnish with tarragon sprigs.