In a large bowl, combine the rye flour, all-purpose flour, caraway seeds, salt, and sugar.
In a small bowl, dissolve the yeast in warm water. Let it sit for about 5 minutes until it becomes frothy.
Pour the yeast mixture into the flour mixture and stir until a dough forms.
Turn the dough out onto a floured surface and knead for about 10 minutes until smooth and elastic.
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.
Preheat your oven to 450°F (230°C). Place your Dutch oven in the oven to preheat as well.
Once the dough has risen, punch it down and shape it into a round loaf. Place it on a piece of parchment paper.
Carefully remove the Dutch oven from the oven and place the dough (with the parchment paper) into the pot. Cover with the lid.
Bake for 30 minutes with the lid on, then remove the lid and bake for an additional 15 minutes, or until the bread is golden brown and sounds hollow when tapped.
Remove the bread from the Dutch oven and let it cool on a wire rack before slicing.