Sift flour, salt, and baking powder in a large bowl. Set aside. Combine rest of ingredients and let proof about half an hour or until the mixture is very foamy.

Add flour mixture into wet ingredients. Knead dough by hand for 10 minutes or until there is no more flour at the bottom of the bowl. Can be kneaded with a machine using a dough hook. Place in a greased bowl and let rise in a warm place for one hour or until doubled in size.

Braid challah. Prepare egg wash by beating one egg with one tablespoon water, brush over loaves, and let rise for half hour. 

Brush with egg wash again. Place in an oven preheated to 450 degrees for 15 minutes. Lower oven to 350 degrees and continue baking until challahs are brown and no longer heavy. Cool on a cooling rack.