1. In a mixing bowl, combine rye flour, all-purpose flour, caraway seeds, salt, and sugar.
2. Dissolve yeast in warm water and let it sit for 5 minutes.
3. Add the yeast mixture to the dry ingredients and mix until a dough forms.
4. Knead the dough on a floured surface for about 10 minutes.
5. Place the dough in a greased bowl, cover, and let it rise for 1 hour.
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.