Horseradish Mashed Potatoes With Caramelized Onions

Recipe by lazyme
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.