Two-Toned Mashed Potatoes

Bring a large pot of water to a boil.

Combine 1 tablespoon buttermilk, creme fraiche (or sour cream), onion powder (or granulated onion) and pinch of salt. Cover and refrigerate while you cook the vegetables.

Add potatoes, sweet potatoes and leek to the boiling water and return to a boil. Reduce heat to maintain a vigorous simmer and cook until tender enough to pierce with a knife, 12 to 15 minutes. Drain and return the vegetables to the pan (off the heat).

Add the remaining 2/3 cup buttermilk, the remaining 3/4 teaspoon salt, butter and pepper to the pan; coarsely mash with a potato masher. Serve topped with the sauce and chives.