Golden brown on the outside, soft and savory on the inside, the square potato knish is a beloved classic in Jewish comfort food. Often found in New York delis and bakeries, these square parcels of flaky dough filled with creamy mashed potatoes are a nostalgic treat for many. While the traditional round knishes are more common, the square version has a special charm, often associated with street vendors and old-school knisheries. Making them at home is not only satisfying but also allows for customization of texture and flavor. With a few basic ingredients and some care in preparation, you can bring the taste of a bygone era to your own kitchen.
Understanding the Square Potato Knish
What Makes It Different
While knishes can come in various shapes and sizes, the square potato knish stands out for its form and history. These are typically baked, though some versions are fried, and are filled with seasoned mashed potatoes. The square shape allows for a uniform crust and filling ratio, which is key to their unique bite and appearance.
Traditional Origins
Knishes originated in Eastern Europe and made their way to the United States with Jewish immigrants. Over time, they evolved into a popular snack, particularly in cities like New York. The square shape is believed to have been introduced by commercial bakeries looking for a more efficient way to mass-produce knishes without sacrificing taste or texture.
Ingredients for Square Potato Knish
For the Dough
- 2 cups all-purpose flour
- 1/4 cup vegetable oil
- 1/2 teaspoon salt
- 1/2 teaspoon baking powder
- 1 teaspoon white vinegar
- 1/2 cup warm water (more if needed)
For the Filling
- 4 medium russet potatoes, peeled and cubed
- 1 medium onion, finely chopped
- 2 tablespoons vegetable oil or schmaltz (chicken fat for traditional flavor)
- Salt and pepper to taste
- Optional: a pinch of garlic powder or paprika
For Finishing
- 1 egg, beaten (for egg wash)
Preparing the Filling
Step 1: Cook the Potatoes
Boil the cubed potatoes in salted water until they are fork-tender, about 15-20 minutes. Drain well and mash until smooth. Do not add milk or butter; the goal is a thick, dense mash suitable for filling.
Step 2: Sauté the Onions
In a skillet, heat oil or schmaltz over medium heat and cook the chopped onions until golden brown and caramelized, around 10 minutes. Stir occasionally to prevent burning.
Step 3: Combine the Filling
Mix the sautéed onions into the mashed potatoes. Season generously with salt and pepper. Add garlic powder or paprika if desired. Let the mixture cool to room temperature before using it as a filling.
Making the Knish Dough
Step 1: Mix the Dry Ingredients
In a large mixing bowl, whisk together the flour, salt, and baking powder. These dry ingredients form the base for the tender but structured dough needed for folding and sealing the square potato knish.
Step 2: Add Liquids
In a separate bowl, combine the oil, vinegar, and warm water. Slowly add this mixture to the flour, stirring until a soft dough forms. Knead gently for a few minutes until smooth. If the dough is too sticky, add a little flour; if too dry, add a few drops of water.
Step 3: Rest the Dough
Cover the dough with a damp cloth or plastic wrap and let it rest for 30-45 minutes. This allows the gluten to relax and makes rolling easier.
Shaping and Filling the Square Knishes
Step 1: Roll the Dough
Divide the dough into 4 equal parts. Roll each portion into a thin rectangle, about 1/8-inch thick. The thinner the dough, the flakier the result. Use flour as needed to prevent sticking.
Step 2: Add the Filling
Place a generous spoonful of potato filling in the center of the rolled dough. Fold the edges over to create a square or rectangular parcel, sealing tightly to prevent leakage. You can use a bit of water to help seal the edges if necessary.
Step 3: Arrange and Brush
Place each filled knish seam-side down on a baking sheet lined with parchment paper. Brush the tops with beaten egg for a glossy finish.
Baking the Knishes
Step 1: Preheat the Oven
Preheat your oven to 375°F (190°C). Ensure the oven is fully heated before baking for the most even browning.
Step 2: Bake Until Golden
Bake the knishes for 30-40 minutes, or until the tops are golden brown and slightly crisp. Rotate the tray halfway through baking for even color.
Step 3: Cool Before Serving
Let the knishes cool slightly on a wire rack before serving. They’re best enjoyed warm, though they can also be reheated and enjoyed later.
Serving Suggestions
Perfect Accompaniments
Square potato knishes pair wonderfully with:
- Spicy brown mustard
- Pickles or sauerkraut
- Soup, especially chicken broth or matzo ball soup
- Applesauce for a sweet contrast
Make It a Meal
Serve your knishes alongside a fresh salad or grilled vegetables for a complete and satisfying meal. They can also be a hearty snack on their own, especially when made slightly larger.
Storing and Reheating
How to Store
Allow the knishes to cool completely before storing. Wrap them individually in plastic wrap or place them in an airtight container. They can be kept in the refrigerator for up to 4 days.
Freezing Tips
Square potato knishes freeze very well. Wrap each one in foil and place in a freezer-safe bag. To reheat, bake at 350°F (175°C) for 20-25 minutes from frozen, or until heated through.
Making a traditional square potato knish recipe at home is both rewarding and delicious. With its flaky dough and rich, seasoned potato filling, it’s no wonder the knish has remained a favorite for generations. This classic dish brings together old-world flavor with the comforting satisfaction of home cooking. Whether enjoyed as a snack or part of a larger meal, square potato knishes are an ideal way to connect with culinary history while indulging in something wonderfully hearty and satisfying.