High-Altitude Challah - cooking recipe

Ingredients

1/2 cup warm water (110 degrees F/45 degrees C)
3 tablespoons white sugar, divided
2 (.25 ounce) packages active dry yeast
2 eggs
2 egg yolks
1/4 cup milk, or as needed
1/4 cup butter or margarine, melted
1 1/2 teaspoons salt
3 1/2 cups all-purpose flour
1 egg

Preparation

Combine the warm water, 1/2 teaspoon of sugar and the yeast in a measuring cup. Let stand until the yeast dissolves and starts to foam, 5 to 10 minutes.
In a large bowl, beat 2 eggs. Put the egg yolks in a measuring cup and add enough milk to equal 1/3 cup with the yolks in it. Pour this in with the eggs and then stir in the yeast mixture, butter, salt and remaining sugar. Gradually mix in the flour until the dough is firm enough to handle. Knead the dough on a floured surface until the dough does not stick to your hands. You will probably use more flour while kneading. Place the dough into an oiled bowl and turn to coat. Cover and let rise until doubled in size, about 1 hour.
Cut the dough into 3 or 4 even portions and roll into long ropes. Braid and tuck the ends under. Place the loaf on a baking sheet and cover loosely with plastic wrap. Set in a warm place to rise. Bread is ready to bake when your finger leaves an impression in the dough.
Preheat the oven to 350 degrees F (175 degrees C). Whisk the remaining egg in a cup with a fork. Brush onto the loaf. This will give the bread a lovely golden color and delicious crust.
Bake until the loaf is golden and the loaf sounds hollow when tapped on the bottom, about 35 minutes. Remove from the baking sheet and cool on a wire rack.