One recipe for German rye bread calls for heating 2 cups of warm water to 110 to 115 degrees Fahrenheit and dissolving 1 1/4-ounce package of active dry yeast in the water. Whisk in 2 cups of rye flour.
Cover the mixture with a clean towel, and let it stand in a warm area for around four hours. Stir in 6 tablespoons of sugar, 2 tablespoons caraway seeds, 2 teaspoons salt, 5 cups of all-purpose flour and 2 more cups of warm water. Stir in up to 3 more cups of all-purpose flour until the dough is firm. Turn the dough onto a floured surface, and knead it for about eight minutes or until it is elastic and smooth. Cover it again, and let it rest for 15 more minutes.
Divide the dough into four equal portions, and cover each portion, letting the portions rest for 15 minutes. Shape the dough into loaves, spray baking sheets with cooking spray, place each loaf on the baking sheet, and let the dough rise until it doubles. Make several slashes in the tops of the loaves brush with egg, and bake for 30 to 35 minutes at 400 degrees.