Blueberry Challah

2 cups blueberries
1 1/4 cups granulated sugar, divided
1 1/4 cups water, divided
1 tablespoon yeast
10 cups white bread flour, divided
1 1/2 teaspoons salt
1/2 pound margarine
3 eggs
2 egg yolks

Mix blueberries with 1/2 cup sugar and 14 cup water. Cook over low heat, stirring occasionally, until the sugar is dissolved. Cool and pureé blueberries. Dissolve yeast in 1 cup water in a large bowl. With a fork, stir in 2 cups flour. Let rise half an hour.

In another bowl, add salt and remaining sugar to 5 cups flour. Cut butter in with a knife or pastry blender until mixture resembles coarse meal. Beat 2 eggs and yolks; add eggs and blueberries to yeast mixture and stir well. Stir in flour mixture.

Turn out onto a floured work surface and knead until dough is smooth and elastic, adding flour as needed, 10 to 15 minutes. Cover with a towel and let rise two hours, or until doubled. (over) Punch down and knead lightly for a minute or two. Divide dough into small balls (9 for three-strand braids, 12 for four-strand). Roll balls into long strands and braid.

Place on an oiled or parchment-lined baking sheet and let rise 3 to 5 hours, or until loaves are well-risen.

Beat the remaining egg and add enough water to make a thick wash. Brush egg wash on loaves and bake at 350 degrees F for 40 minutes, or until loaves are brown and sound hollow when tapped. Allow to cool before slicing.