The ingredients in knish include potatoes, onions, parsley, eggs and flour along with vinegar, water, oil, salt and pepper. This recipe is a type of bread roll with a potato filling and a traditional Jewish favorite.
To make knish, cook 4 sliced onions in 2 tablespoons of vegetable oil for 20 minutes until they are soft and caramelized, and mix them along with 2 1/2 pounds of cooked and mashed russet potatoes, 1 egg, 1/2 cup of chopped parsley, 1 teaspoon of salt and pepper to taste in a bowl. In another bowl, beat 2 eggs until well combined, setting 1 tablespoon of the mixture aside.
Combine the rest of the beaten eggs with 1/2 cup of vegetable oil, 1 cup of water, 1 tablespoon of white vinegar and 1/2 teaspoon of salt before gradually mixing in 4 cups of all-purpose flour. Knead the dough into 4 balls, and cover them for 15 minutes.
Roll each dough ball out into a thin rectangle, and spoon the potato mixture into the middle of the dough sheets. Roll the dough up, pinch the ends shut, and place them on a baking sheet. Brush the reserved egg mixture of the tops of the rolls, and bake them at 375 degrees Fahrenheit for 25 to 30 minutes.