This popular bread (Smørbrøds Brød) is used in Denmark for open-face sandwiches; it should be sliced about an inch thick. It can be made without the wheat flour; the wheat flour helps the loaf rise more quickly.
In a large bowl, combine 1 cup water, 1 tablespoon yeast, 1 tablespoon sugar, and 1 cup rye flour. Cover batter with a damp cloth, and place in a warm, draft-free spot.
In the evening, mix in 1 teaspoon yeast, 1 teaspoon sugar, 1/2 cup warm water, and 1 cup rye flour. Cover again, and set aside overnight.
In the morning, mix in 1 tablespoon sugar, 1 tablespoon kosher salt, and 1 cup warm water. Gradually mix in 2 cups rye flour and 1 cup of all-purpose flour (if using). When the dough has pulled together, turn it out onto a lightly floured surface and knead for about 5 minutes. Form into a loaf, and place on a baking sheet. Allow to rise for about 40 minutes.
Preheat oven to 375 degrees F (190 degrees C). Bake for about 30 minutes, or until the bottom of the loaf sounds hollow when tapped.
Per Serving: 172 calories; protein 4.8g; carbohydrates 37.2g; fat 0.8g; sodium 483.4mg.