A healthier way to enjoy mashed potatoes.
1.5 lbs new potatoes, peeled and cut into cubes
1 lb turnips, trimmed, peeled and cut into cubes
2-3 tablespoons extra-virgin olive oil
1 leek, white and light green portions thinly sliced
1/4 cup sour cream
1/2 tsp. salt
1/2 tsp. black pepper