Challah
Servings: 16
Start to finish: 3 3/4 to 4 3/4 hours, plus 3 hours cooling time (Rising time: 2 1/2 to 3 1/2 hours)
Key Equipment: 2 rimmed baking sheets, pastry brush, instant-read thermometer
3 1/4 cups (16 1/4 ounces) all-purpose flour
2 1/4 teaspoons instant or rapid-rise yeast
1 1/4 teaspoons salt
1/2 cup (4 ounces) water, room temperature
1/4 cup (1 3/4 ounces) vegetable oil
2 large eggs plus 1 large yolk, room temperature
1/4 cup (1 3/4 ounces) sugar
1 large egg, lightly beaten with 1 tablespoon water and pinch salt
1 teaspoon poppy or sesame seeds (optional)
Whisk flour, yeast, and salt together in bowl of stand mixer. Whisk water, oil, eggs and yolk, and sugar in 4-cup liquid measuring cup until sugar has dissolved.
Using dough hook on low speed, slowly add water mixture to flour mixture and mix until cohesive dough starts to form and no dry flour remains, about 2 minutes, scraping down bowl as needed. Increase speed to medium-low and knead until dough is smooth and elastic and begins to pull away from sides of bowl but sticks to bottom, about 10 minutes.
Transfer dough to lightly floured counter and knead by hand to form smooth, round ball, about 30 seconds. Place dough seam side down in lightly greased large bowl or container, cover tightly with plastic wrap, and let rise until increased in size by about half, 1 1/2 to 2 hours.
Stack two rimmed baking sheets, line with aluminum foil, and spray with vegetable oil spray. Transfer dough to clean counter and divide into 2 pieces, one twice as large as the other (small piece will weigh about 9 ounces, larger piece about 18 ounces). Divide each piece into thirds and cover loosely with greased plastic.
Working with 1 piece of dough at a time (keep remaining pieces covered), stretch and roll into 16-inch rope (three ropes will be much thicker).
Arrange three thicker ropes side by side, perpendicular to counter edge, and pinch far ends together. Braid ropes into 10-inch loaf and pinch remaining ends together. Repeat braiding remaining ropes into second 10-inch loaf.
Transfer larger loaf to prepared sheet, brush top with egg mixture, and place smaller loaf on top. Tuck ends underneath. Cover loosely with greased plastic and let rise until loaf increases in size by about half and dough springs back minimally when poked gently with your knuckle, 1 to 1 1/2 hours.
Adjust oven rack to middle position and heat oven to 375 degrees. Brush loaf with remaining egg mixture and sprinkle with poppy seeds, if using. Bake until deep golden brown and loaf registers 190 to 195 degrees, 20 to 25 minutes, rotating sheet halfway through baking. Transfer loaf to wire rack and let cool completely, about 3 hours, before serving.
