1. In a mixing bowl, combine the rye flour, all-purpose flour, caraway seeds, salt, and sugar.
2. Dissolve the yeast in warm water and let it sit for about 5 minutes until frothy.
3. Add the yeast mixture to the dry ingredients and mix until a dough forms.
4. Knead the dough for about 10 minutes until smooth and elastic.
5. Place the dough in a greased bowl, cover, and let it rise in a warm place for about 1 hour or until doubled in size.
6. Preheat the oven to 375°F (190°C).
7. Punch down the dough, shape it into a loaf, and place it on a baking sheet.
8. Bake for 30 minutes or until the bread sounds hollow when tapped.
9. Let the bread cool on a wire rack before slicing.