1 lb potatoes
½ cup finely chopped onions
1 shallot finely chopped (optional)
1 large egg, lightly beaten
½ tsp salt
½ to ¾ cup good olive oil
Preheat oven to 250º
Peel potatoes and coarsely grate by hand, transferring to a large bowl of cold water as grated.
Spread grated potatoes and onion on a clean kitchen towel and roll up like a jelly roll. Twist towel tightly to wring out as much liquid as possible.
Place in mixing bowl and add egg and salt.
Heat a cast iron skillet over medium heat. When skillet is hot:
Add ¼ tsp of olive oil and a slice of butter to the hot pan and immediately add 2 tablespoons of mixture per latke and spread into three inch circles with a fork.
Cook until undersides are browned, about 5 minutes. Flip and brown other sides.
Add oil and butter as needed for each batch of latkes. Keep latkes warm on a wire rack set in a shallow pan in oven.