Adapted from Cook’s Country
- 475 ml (2 cups) warm (not boiling) water
- 1 tablespoon sugar
- 2 teaspoons instant or rapid-rise yeast
- 675 g (4 ¾ cups) plain (all-purpose) flour
- 1 tablespoon table salt
- 3 tablespoons vegetable oil
- 3 onions medium, peeled and chopped fine
- 1 teaspoon table salt
- ½ teaspoon sugar
- 1 tablespoon poppy seeds
FOR THE DOUGH
In the bowl of a stand mixer, combine warm water, sugar, and yeast and let sit until foamy, about 3 minutes. Add flour and salt to the yeast mixture. Fit stand mixer with the dough hook and knead on low speed until the dough comes together, about 3 minutes.
Turn out dough onto a lightly floured counter and knead by hand until smooth, about 1 minute. Transfer dough to a greased bowl and cover tightly with plastic wrap. Let dough rise at room temperature until almost doubled in size, about 1 hour.
Line 2 baking sheets with baking paper and lightly flour parchment. Gently press the center of the dough to deflate. Transfer dough to a lightly floured counter and divide into 13 x 85-gram pieces (or just eyeball it). Form each piece into a rough ball by pulling dough edges underneath so the top is smooth. Arrange 6 balls on each prepared sheet and cover loosely with plastic. Let dough rise at room temperature for 30 minutes.
FOR THE FILLING
Heat oil in a large nonstick saute over medium heat until shimmering. Add onions and salt and sugar, stirring occasionally to ensure that the onions don’t catch on the bottom of the pan, cook until golden brown, about 10 minutes. Off heat, stir in poppy seeds.
Heat oven to 220℃ (430℉). On a lightly floured counter, use your hands to gently press each dough ball into 5-inch rounds. Return to sheets and cover loosely with plastic. Let dough rise at room temperature until puffy, 15 to 20 minutes.
Grease and flour bottom of a round 1-cup dry measuring cup (or 7-cm-diameter drinking glass). Press cup firmly into the center of each dough round until the cup touches the sheet to make an indentation for filling, (reflour cup as needed to prevent sticking).
Divide filling evenly among bialys (about 1 heaping tablespoon each) and smooth with the back of the spoon. Bake until golden brown, 15 minutes, rotating and switching sheets halfway through baking. Transfer bialys to a wire rack and let cool for 10 minutes. Serve.