Dissolve yeast in 1 cup warm water in a large bowl; stir in honey and saffron threads.
Let stand for 5 minutes.
Add melted butter, 1 teaspoon salt, and egg; stir well with a whisk.
Lightly spoon flour into dry measuring cups; level with a knife.
Add 2 3/4 cups flour to yeast mixture, and stir until a soft dough forms. Cover and let stand for 15 minutes.
Turn dough out onto a lightly floured surface. Knead until smooth and elastic (about 8 minutes); add enough of remaining flour, 1 tablespoon at a time, to prevent dough from sticking to hands (dough will be very soft).
Place dough in a large bowl coated with cooking spray, turning to coat top. Cover and let rise in a warm place (85), free from drafts, 40 minutes or until doubled in size. (Gently press two fingers into dough. If indentation remains, the dough has risen enough.)
Punch dough down. Shape dough into a ball; return to bowl. Cover and let rise an additional 40 minutes or until doubled in size. Punch dough down; cover and let rest 15 minutes.
Divide dough into 3 equal portions. Working with 1 portion at a time (cover remaining dough to prevent drying), on a lightly floured surface, roll each portion into a 25-inch rope with slightly tapered ends.
Place ropes lengthwise on a large baking sheet sprinkled with cornmeal; pinch ends together at untapered ends to seal. Braid ropes; pinch loose ends to seal. Cover and let rise 20 minutes or until almost doubled in size.
Preheat oven to 37
Combine 1 teaspoon water and large egg yolk, stirring with a fork until blended. Uncover loaf, and gently brush with egg yolk mixture.
Sprinkle evenly with 1/4 teaspoon poppy seeds.
Bake at 375 for 30 minutes or until loaf sounds hollow when tapped. Cool on a wire rack.
