Sourdough Potato Bread

1 package active dry yeast
5 1/2 - 6 cups flour
1/4 cup sugar
2 tsp. salt
Instant mashed potatoes(amount for 2 servings) plus ingredients below as
specified on package:
milk
butter
salt
3/4 cup milk
1/4 cup butter or margarine, melted and cooled
2 eggs
1 cup sourdough starter, at room temperature
1 egg white beaten with 2 Tbsp. water

In large bowl of electric mixer, combine yeast, 2 cups flour, sugar, and
salt. In pan prepare mashed potatoes according to instructions on
package. Then add to the potatoes 3/4 cup milk, 1/4 cup butter, eggs, and
starter--stir until blended.

Add potatoes to dry ingredients and beat at medium for 2 minutes,
scrapping sides. Add 1 1/2 cups flour and beat at medium for 2 minutes.
With heavy mixer or wooden spoon, add enough of remaining flour to make a
stiff dough.

Knead dough on floured surface until smooth(5-20 min.) adding flour to
prevent sticking. Place dough in greased bowl--turn over to grease top.
Cover and let rise in warm place until doubled(1 1/2 - 2 hrs.) Punch
dough down. Knead briefly to release air. Divide in half.

Shape each half into a smooth ball and place each on a lightly greased
12x15" baking sheet. With a sharp floured knife, cut 1/2" deep slashes in
the tops of loaves in a tic-tac-toe pattern.

Cover loaves and let rise until almost doubled(45 min.) Brush loaves with
egg white mixture. Bake in preheated 350 degree oven for about 35 min. or
until loaves are richly browned. Let cool on racks. Makes 2 large
loaves.