Potato Kreplach

Make the dough: Combine the flour, lemon zest, and salt in a food processor. With the blade running, add eggs and olive oil. Add additional water, as needed (1 tablespoon at a time) until a dough forms. Roll into a ball, and cover with plastic wrap. Refrigerate for 15-30 minutes.

Meanwhile, prepare the filling: Heat the olive oil in a pan over medium heat. Add the onion, and cook until softened and golden, about 15-20 minutes. Add to the leftover mashed potatoes, and season generously with salt and pepper.

Combine cornstarch and water in a small bowl.

On a lightly floured surface, roll the dough to 1/8th inch thickness. Use a paring knife or pizza roller to cut the dough into 3-inch squares.

Using your finger, run the cornstarch mixture around the edges of each square. This acts as glue.

Place 1 to 1 1/2 tsp of potato filling in the middle of each square.

Fold into a triangle, and join the ends.

Place on a floured tray, and repeat with all the filling and dough.

Bring a large pot of salted water to boil. Cook the kreplach for 2-3 minutes or until they float to the surface.

Serve with broth, or alongside fried onions.