Ingredient:

• 3 pounds russet potatoes, peeled and quartered
• 1 1/2 teaspoons salt, divided
• 1 teaspoon olive oil
• 2 cups chopped onions
• 3 cloves garlic, minced
• 1 tablespoon sugar
• 1 tablespoon white vinegar
• 1 1/2 cups sour cream
• 1 cup buttermilk
• 1/4 cup salted butter
• 1/2 teaspoon freshly ground black pepper
• 4 green onions, chopped
• 1 bunch green chives, chopped, plus more for garnish
• 1/2 cup shredded white Cheddar cheese
• 1/2 cup crushed sour cream and onion potato chips