2 1/4 cups
all-purpose flour, plus more for rolling out the dough
1 teaspoon
baking powder
1/2 teaspoon
kosher salt
1
large egg, lightly beaten
8 tablespoons
unsalted butter, melted and cooled
1 teaspoon
distilled white vinegar
1/2 cup
lukewarm water
4 tablespoons
unsalted butter
2
large white or yellow onions, thinly sliced
1 teaspoon
kosher salt
1/2 teaspoon
freshly ground black pepper
1 teaspoon
granulated sugar
2
medium leeks, whites only, trimmed, cleaned, and thinly sliced
1/4 cup
water, plus one teaspoon
1 pound
Yukon gold potatoes, peeled
6 ounces
all-natural cream cheese
1 bunch
fresh chives, minced (about 1/4 cup)
1/4 cup
Parmigiano-Reggiano cheese, finely grated (optional)
1 1/2 teaspoons
white or black sesame seeds
1 teaspoon
poppy seeds
1 teaspoon
caraway seeds
1 tablespoon
dried onion flakes
1
large egg, beaten