Horseradish Mashed Potatoes With Caramelized Onions

"From Bon Appetit, a nice side dish that can be made ahead. ZWT West region (Idaho potatoes)."
photo by sassafrasnanc photo by sassafrasnanc
photo by sassafrasnanc
photo by Debi9400 photo by Debi9400
photo by Rita1652 photo by Rita1652
photo by Rita1652 photo by Rita1652
Ready In:
1hr 20mins


  • 14 cup butter
  • 2 14 lbs white onions, thinly sliced
  • 3 tablespoons balsamic vinegar
  • 2 teaspoons fresh thyme, chopped
  • 3 12 lbs russet potatoes, peeled, cut into 1-inch pieces
  • 7 tablespoons whole milk
  • 14 cup prepared horseradish
  • 6 tablespoons butter


  • Melt 1/4 cup butter in large skillet over medium heat. Add onions; saute until deep golden, about 30 minutes. Add vinegar and thyme. Reduce heat to low; saute 4 minutes. Season with salt and paper.
  • Meanwhile, cook potatoes in large pot of boiling salted water until very tender, about 20 minutes. Drain. Return to same pot; mash until smooth. Add 6 tablespoons milk, horseradish and 6 tablespoons butter; stir to blend. Thin with 2 tablespoons milk if necessary. Add 1 to 2 tablespoons more butter if necessary. Season with salt and pepper.
  • Transfer potatoes to serving dish. Spoon onion mixture atop potatoes. (Can be prepared 8 hours ahead. Cover with foil and refrigerate. Rewarm in 350ºF oven about 30 minutes). Serve hot.

Questions & Replies

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  1. Loved this recipe! We enjoyed the sweetness of the carmelized onions with the strong flavor of the horseradish! Served this with "Recipe #305341" for a totally German dinner! Also served a cucumber salad with this dinner. ZWT4.
  2. Wonderful! Perfect amount of horseradish. I thought it would be overpowering but the taste came through without to much heat. I used 1/2 cup low fat milk and 3 pounds of potatoes that I used my ricer for fluffy tatars! Thanks!!!
  3. This was a nice dish that presents beautifully. Some of us liked the carmelized onions and some of us found them too sweet. Averaged out the families' ratings and came to a solid 4.
  4. This was good, although next time I may add more horseradish, as the flavor wasn't quite there. I also added a couple of garlic cloves, minced to the onions. If you make it ahead of time and refrigerate it first, I would suggest taking it out about 30 minutes prior to reheating it. I reheated for 30 minutes and it wasn't as hot as it should have been and had to put it back in for another 10-15 minutes.


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