These Caramelized Onion Mashed Potatoes are a step above the classic side dish. The slightly sweet, deep, and savory flavors of the creamy mashed potatoes and golden brown onions are completely irresistible and pair so well with dinner.
Heat a large saucepan to low heat (or medium-low if your stove doesn’t get as hot), add olive oil, butter, and thinly sliced onions. Stir to coat the onions in the oil. Sprinkle the onions with 1 teaspoon of salt, lower the heat and cook over low heat, stirring occasionally, until the onions are soft and darker in color, around 20-25 minutes.
Increase heat to medium, add the red wine and vinegar. Simmer until all the wine is cooked off, and the onions are very soft and caramelized, about 5-7 minutes. Season to taste with any additional salt and set aside. Note: This can be made up to 3 days in advance and kept in an airtight container in the fridge.
Mashed potatoes
In a small saucepan, gently warm the cream and butter until the butter is melted. Keep warm.
Place the cubed potatoes and bay leaves in a medium pot, cover with cold water, add 5 tablespoons of salt, or more to taste. Bring to a simmer over medium heat and simmer until potatoes are fork-tender, about 10-15 minutes.
Remove bay leaves. Drain the potatoes in a colander and add to a bowl. Using a potato masher or ricer, gently mash the potatoes in the pot.
Add the warmed cream and butter mixture and the sour cream to the potatoes and mash until smooth. Add the caramelized onions, and stir until smooth. Top with fresh dill. Serve immediately.