1) Peel and grate the parsnips and potatoes and rinse them gently under cold water.
2) Lay out the grated veggies on a few paper towels or a clean kitchen towel and pat them dry. The drier the better.
3) Stir together grated potatoes and parsnips with chives, egg whites, cornstarch, 1 teaspoon of kosher salt and a big pinch of black pepper. Stir together well.
4) In a large skillet, heat 2 tablespoons of butter and two tablespoons of oil over medium-high heat. Stir together as butter melts.
5) Working with about 1/3 cup of potato mixture, wring it out to remove some of the liquid, the add it to the hot pan and use a spatula to gently press it flat. Repeat until the pan is full. Try not to crowd the latkes too much so they brown nicely.
6) Fry latkes over medium-high heat for about five minutes per side. They should be really nicely browned.
7) Remove cooked latkes and let drain on a paper towel. Repeat until all the potato mixture is used. Add more butter and oil to the pan as needed to keep the pan well-oiled.
Serve latkes immediately with sour cream and chives or keep them warm in a 250 degree oven until you serve them.