Roasted Garlic Potato Knishes

Ingredients

• 1¾ cups all-purpose flour
• 1½ teaspoons sugar
• 1 teaspoon kosher salt
• ¼ cup vegetable or grapeseed oil, plus more as needed
• ½ cup lukewarm water
• 1 head garlic
• 1 teaspoon extra-virgin olive oil
• ¼ cup schmaltz (page 35) or vegetable oil, plus more for the knishes
• 2 medium onions, diced
• 4 teaspoons kosher salt, plus more as needed
• 1½ pounds russet potatoes (about
• 4 medium), peeled and cut into 2-inch chunks
• ½ teaspoon freshly ground black pepper
• ¼ cup all-purpose flour, for dusting
• Vegetable oil
• 1 egg, beaten
• Mustard, for serving