2 tbsp. chopped onion
4 tbsp. butter, softened
2 tsp. poppy seed
2 tbsp. mustard
1 tbsp. horseradish

Mix above ingredients together. Spread on both sides of a bun or kaiser roll. Then alternate slices of ham, tomato, and Swiss cheese to complete sandwich. Wrap in foil and bake 10 to 15 minutes in a 350 degree oven or wrap in waxed paper and microwave on medium until cheese begins to melt.