Mashed Potatoes

Ingredients

• 1 tablespoon extra-virgin olive oil
• 3 tablespoons unsalted butter, at room temperature, divided
• 2 medium yellow onions, sliced (¼-inch; about 4 cups)
• 1 tablespoon sherry vinegar
• 2 pounds Yukon Gold potatoes (about 6), peeled and cut into 2-inch pieces
• ¾ cup whole milk, warmed
• 1¼ teaspoons salt
• Ground pepper to taste
• Fresh thyme leaves for garnish (optional)

Instructions

1. 1Heat olive oil and 1 tablespoon of butter in a large skillet over medium heat until the butter is melted
2. 2Add onions and cook, stirring occasionally, until starting to brown, about 10 minutes
3. 3Reduce heat to low, cover and cook, stirring occasionally, until the onions are very soft and golden brown, about 20 minutes
4. 4Stir in sherry vinegar and cook for 1 minute
5. 5Meanwhile, place potatoes in a large saucepan and add enough water to cover by 1 inch
6. 6Bring to a boil over high heat, then reduce heat to maintain a simmer
7. 7Cook until the potatoes are very tender when pierced with a fork, 15 to 20 minutes
8. 8Drain the potatoes and return them to the pan
9. 9Add the remaining 2 tablespoons of butter and mash until mostly smooth
10. 10Gradually add milk, salt and pepper, mashing until creamy
11. 11Serve the mashed potatoes topped with the caramelized onions and thyme leaves, if desired