Once you make a few hundred pies, everything begins to look like a pie. And that is how I came to define a knish as a kinda-pie, a pastry wrapped around filling. In fact, I put empanadas, calzones and samosas in the same category.
A knish (the K is voiced: ka-nish) is a classic filled pastry. While potato knishes are most common, there are other fillings, too, and it’s a good way to use up leftovers.
A knish recipe often calls for dough that is both dairy- and meat-free, avoiding butter or animal fat, and using oil instead, which permits a kosher household (where dairy and meat are not mixed) to stuff the pastry with either filling.
The dough, whisked with a fork, comes together quickly. It is reminiscent of strudel dough, but is even more elastic. It can be pulled to size like strudel, but it’s bouncy and resistant, so a rolling pin is easier. I mark off a 12-by-12-inch space on the counter using painters’ or masking tape, so I can aim for the correct size and shape. It will seem as if the dough will not fill that space, but it will, and it will be whisper thin. There is no need to flour the counter; this oily dough will not stick. I place a log of filling near the edge of the square and roll it up like a fat cigar, pinching the edge to seal.
Shaping the knish is like forming sausage; use a sharp knife or scissors to snip the long cylinder into six even pieces. Shape the knish by lifting and pinching together the edges of the dough. I like to leave the tops open so the filling is exposed, but it’s also possible to crimp the top closed. Be careful not to compact the potato filling too much, as it expands during baking .
Classic Potato Knishes
Makes 18 knishes
For the dough:
½ cup canola oil, or another neutral oil
¼ to 1/3 cup cool water
1 large egg
1 teaspoon white vinegar
½ teaspoon kosher salt
Scant 2½ cups flour
1 teaspoon baking powder
For the filling
1¾ pounds russet potatoes (about 4 medium)
¾ cup creme fraiche or sour cream
4 tablespoons unsalted butter
¼ cup snipped chives
¼ cup chopped fresh flat-leaf parsley
1 teaspoon kosher salt
½ teaspoon freshly ground black pepper
For the egg wash
1 large egg
1 tablespoon cool water
¼ teaspoon kosher salt
Make the dough: In a medium bowl, whisk together the oil, ¼ cup water, 1 egg, the vinegar and salt. In a large bowl, combine the flour and baking powder. Make a well in the dry ingredients and pour in the liquid ingredients. Using a fork, stir until a rough ball is formed. With your hands, working in the bowl, knead the ball of dough until smooth and elastic, about 8 minutes. Cover the bowl and let the dough rest for 1 hour.
Make the filling: Preheat the oven to 350 F with the rack in the middle.
Scrub the potatoes and pierce them with a knife in a few places. Bake the potatoes directly on the oven rack for 55 to 60 minutes.
Remove the potatoes from the oven and, holding a hot potato with a dry towel, make a vertical slit across the top. Squeeze at both ends to open the potato and release the steam. Using a fork, fluff the potato, then scrape it out of the peel into a large bowl. Repeat with the remaining potatoes.
Add the creme fraiche, butter, chives, parsley, salt and pepper to the potatoes and stir and mash with a fork, a potato masher, or a sturdy whisk until the potatoes are smooth and creamy. Cool completely.
Assemble the knishes: Preheat the oven to 375 degrees and line a baking sheet with parchment paper.
Knead the dough, incorporating back into the dough any oil that pools at the bottom of the bowl. Divide the dough into three pieces; cover two with plastic wrap while working with the first.
Roll out one section of dough into a whisper-thin 12-by-12-inch square. The dough will want to snap back, but use a firm hand to stretch it to size.
Leaving a border of about 1 inch, place 1 cup of the filling along the length of the dough in a long log. Lift the dough edge closest to the filling and stretch it up and over the filling snugly. Don’t fret if the dough tears; just roll it up. You should have a 12-inch log of dough filled with potato.
Place the log parallel to the counter edge and use the side of your hand to indent the roll in 5 places, measuring for 6 knishes, each about 2 inches long. Grasping the log, form each knish by slightly twisting at the indents in opposite directions for 6 pudgy little knishes.
Using a sharp knife, scissors or a pizza wheel, cut between each knish. One end of the knish will inevitably have more dough — that’s the bottom. The other end will have exposed filling. You can either pull the dough up and around the filling to close the knish, pinching the dough together, or leave it open .
Work this way to form 6 pastries, setting each finished knish on the baking sheet. Repeat with the remaining two pieces of dough. You should have 18 knishes on the baking sheet.
In a small bowl, lightly beat the egg with the water and salt until combined. Brush the sides of the knishes with the egg wash and bake for 30 minutes, until deeply golden brown. Transfer to a wire rack and let cool slightly before serving.
Make ahead: The filling may be made 1 day ahead. Knishes may be formed and frozen for up to 3 months, before or after baking.