Step 1

Butter a large bowl; set aside. Stir all remaining ingredients, except the egg for egg wash and the butter for brushing, in a large bowl until well combined. Turn out dough onto a lightly floured work surface; knead dough, adding flour if needed, until smooth and pliable, about 15 minutes.

Step 2

Transfer dough to buttered bowl; brush top with 1 tablespoon melted butter. Loosely cover with plastic wrap. Let dough rise in a warm place until almost doubled in bulk, about 1 1/2 hours.

Step 3

Turn out dough onto a lightly floured work surface; knead 5 minutes, then return to bowl. Brush top with remaining tablespoon melted butter, and loosely cover with plastic wrap. Let dough rise again until doubled in bulk, about 1 hour more.

Step 4

Preheat oven to 375 degrees. Divide dough into three equal pieces. Roll each piece into a ball, and loosely cover each ball with buttered plastic wrap. Let rest 20 minutes.

Step 5

Roll each ball into a 12-inch-long log, leaving the middle a little thicker than the ends. Lay logs side by side lengthwise; pinch together ends farthest from you, then tightly braid strands, pulling them as you go. Tuck ends of braid underneath. Transfer to a buttered baking sheet, and loosely cover with buttered plastic wrap. Let dough rise until almost doubled in bulk, about 45 minutes.

Step 6

Brush dough lightly with egg wash. Bake until golden brown and firm and an instant-read thermometer inserted into bottom registers 180 degrees and comes out clean, 35 to 40 minutes. If challah browns too quickly, loosely tent with foil. Immediately transfer to a wire rack; let cool at least 45 minutes.