Knishes - Potato Filling Recipe

In a large pan, melt the 6 tablespoons of chicken fat over medium heat. Add the 1 cup of diced onions and cook, stirring occasionally, until they're softened and deeply golden brown, about 8-10 minutes. You want them to be sweet and caramelized, not just translucent.

Remove the pan from the heat and add the cooked potatoes, the 1 egg, 6 tablespoons of salt, and 1/4 teaspoon of pepper to the onion mixture. Beat everything together until the potatoes are light and fluffy, incorporating all the ingredients evenly.