Start by stirring the yeast, sugar, and 250 ml warm water. The water should be around 50°C. After you stir the ingredients together, let the mixture sit for 5 minutes until it turns bubbly.
Take the flour and place it in a large mixing bowl. Next, beat 10 quail egg yolks, 5 whole quail eggs, and salt together. After you have a smooth mixture, stir the yeast into the flour along with the smooth egg mixture. Stir these together until shaggy dough forms. If needed, add some lukewarm water.
Next, turn the dough onto a previously floured surface and knead it until it becomes smooth and supple. Try to shape it into a ball, then place it into a lightly oiled bowl. Cover the bowl with a clean towel and let it rise in a warm and draft-free space until it doubles in size.
After 40 minutes, take the dough out of the bowl and punch it down, dividing it evenly into 3 pieces. Roll each of the pieces into 12 inches or 30 cm long ropes. While you do this, make sure the pieces are covered with a clean towel. Next, loosely braid the ropes together in order to make it look like challah and pinch the ends to seal.
Then, transfer to a lightly oiled baking pan. Cover it with a clean towel and let rise in a warm and draft-free space for an hour.
Heat the oven to 200°C. While the oven warms up, beat the remaining 5 quail eggs and lightly brush the loaf of challah with the mixture.
Now, to complete this challah bread recipe, place the loaf in the oven, reduce the temperature to medium-low and bake until the loaf sounds hollow when tapped and is golden brown. This should take 35-40 minutes.
Remove the challah bread loaf from the oven and place it on wire racks. Allow it to cool down completely before cutting into slices.