I got this recipe from my mom's cousin Jeanie, for inclusion in the Family Cookbook I am putting together. It is from her traditional Irish dinner repertoire, and therefore was a perfect accompaniment to my Corned Beef and Cabbage. It is excellent. Thanks, Jeanie!
1/2 cup sour cream
1/2 cup mayonnaise
2 tablespoons or more prepared hot horseradish
1 tablespoon chopped parsley
Mix all ingredients together, adding horseradish to taste. Let stand at least 1 hour before serving.