We discovered a sandwich spread in Italy that was very tasty. It had mustard, mayonnaise, and horseradish. We have played with this combination and here is the recipe that is quite close to the one we liked. Senape is the Italian word for mustard and this is what our guide called the spread.
¾ cup mayonnaise
1 ½ Tablespoon Dijon mustard
1 to 1 ½ teaspoon prepared horseradish
Whisk the mayo, mustard, and horseradish together until smooth. Taste and add more horseradish if preferred.