I use Ina Garten's Recipe for Mustard Horseradish sauce on my standing rib roast... I bet it would be delish on the roasted whole tenderloin of beef
Thank you both for sharing your recipes with me... I will be roasting a whole beef tenderloin for DH's birthday next week...

[color:"blue"]Ina Garten's Mustard Horseradish Sauce:[/color]


1 1/2 cups good mayonnaise
3 tablespoons Dijon mustard
1 1/2 tablespoons whole-grain mustard
1 tablespoon prepared horseradish
1/3 cup sour cream
1/4 teaspoon kosher salt
Whisk together the mayonnaise, mustards, horseradish, sour cream, and salt in a small bowl.