Ingredients

The following ingredients have 35 Servings
  • 1 package puff pastry dough (2 sheets), defrosted if frozen, Note 1 (about 17 ounces dough. )
  • 3 1/2 cups (730g) mashed potatoes (fresh, left over, store-bought or instant) Note 2
  • 2 tablespoons olive oil
  • 1 medium onion, finely chopped
  • 2 tablespoons dry onion soup mix (optional) (or salt and black pepper to taste)
  • 1 egg mixed with1 tablespoon cold water, mixed ((for egg wash))

Instruction

  • Heat oven to 400F/204C.
  • MAKE POTATO MIXTURE: To fry onions, heat oil on medium heat and sauté onions for 5-6 minutes just until slightly brown. Combine mashed potatoes and caramelized onions in a medium bowl with a fork. Season with salt and pepper - or 2 tablespoons of dry onion soup mix - to taste. You can omit the salt and pepper if you are using leftover mashed potatoes that are already seasoned.
  • MAKE KNISHES: You will make two rolls of knishes from each sheet of puff pastry. On a lightly floured surface, unroll one sheet of puff pastry dough. It should be about 1/4 inch/0.63cm thick or less. Stretch out or roll dough a bit if necessary. Spread potato filling to resemble a log  - about 2 inches/5cm thick - along one side of the rolled dough. Fold dough over the potato about 1 1/2 times in a jelly-roll fashion, making a log/roll. Cut away remaining dough with a sharp knife for the next roll. Tuck ends and pinch seams together well (to ensure filling doesn't seep out). Repeat with other half of dough on the same sheet of dough. Then do the same with the second sheet of dough. If you have extra dough and potato mixture left over, make a 5th roll. 
  • BAKE: Place rolls on a large baking sheet lined with parchment paper, seam side down. Brush egg wash on rolls which will create a glazed golden look (optional). Bake for 25-30 minutes to a golden brown flaky pastry. If any potato mixture seeps out, tuck it back into the knish roll with a knife.
  • TO SERVE: Cut rolls of finished knishes into 2 inch/5 cm pieces on the diagonal and serve. To make ahead (recommended!) see Note 2.