Having leftover prime rib from the holidays sets you up to make this simple appetizer to keep your guests happy and impressed. You will need to prepare the horseradish sauce the night before (ingredient and directions below).
- ½ lb. Freshly slice Roast Beef (or you can use the prime rib you may have leftover from the holidays...you never know)
- 3 T of Extra Virgin Olive Oil
- 1-2 White Onions (thinly sliced)
- 1 Loaf Thin French Bread cut into 1/4" thick slices
- 1 cup Sour Cream
- ¼ cup Fresh Finely Grated Horseradish
- 1 T Dijon Mustard
- 1 t White Wine Vinegar
- ½ t Kosher Salt
- ¼ t Fresh Ground Pepper
- Combine the sour cream, horseradish, mustard, vinegar, salt, and pepper in a bowl and whisk until the mixture is creamy and smooth. Place in the refrigerator overnight to chill and let the flavors infuse.
- One the day of the event, add the olive oil to a skillet over medium heat. Add the onions, letting them sweat before reducing the heat to medium-low. Continue stirring for another 20-25 minutes until they are a glassy brown. If you store these in the refrigerator before serving, you can heat these quickly in the microwave before assembling the final appetizer.
- Cut the roast beef into pieces about twice the size of the bread slices (to enable one or more folds).
- Toast the bread slices for 10 minutes in a 350° oven, until slightly toasted (not crisp).
- When the bread comes out, lay the roast beef pieces on the bread. Add a dollop of horseradish sauce on top of the roast beef, and add a string of caramelized onion on top of this (twist the onion into a figure 8 as you lay it on top of the horseradish).
- It's now ready to serve and impress.