Nana Reba’s Potato Knishes

Directions

1. Preheat oven to 350°. Prepare potatoes according to package directions. Meanwhile, in a small skillet, heat butter over medium heat. Add onion; cook and stir just until tender, 4-6 minutes. Remove from the heat. Stir in salt and pepper. Stir onion mixture into potatoes. Cool slightly.
2. Meanwhile, on a work surface, unroll crusts. Roll each to a 12x10-in. rectangle. Spread half the potato mixture evenly over 1 crust; top with another crust. Repeat with remaining crusts and potato mixture. Cut each rectangle lengthwise into 2-in. strips. Carefully transfer strips to parchment-lined baking sheets, separating slightly. Press opposite edges of strips with a fork to seal. Cut strips crosswise into 2-in. squares.
3. Bake until golden brown, 25-30 minutes. Serve warm with mustard.