In a small bowl, combine 1/2 cup of the warm water, yeast and sugar. Let sit in a warm place until the yeast mixture turns bubbly (about 5-10 min.).
In a large mixing bowl (I use my Kitchenaid stand mixer with a dough hook), combine remaining 1 cup water, molasses, salt, shortening, caraway seeds and yeast mixture. Beat until smooth.
Slowly beat rye flour into the yeast and molasses mixture. Mix in the all-purpose flour and mix until it is a soft, smooth dough ball.
Turn the dough out onto a lightly floured surface. If dough is too moist, add a little more flour. If dough is too dry add a little more water.
Knead the dough for 5 minutes.
Lightly grease (or spray with cooking spray) a large bowl. Add the dough, turning once to coat the entire surface of dough with oil. Cover dough with a clean cloth and let rise in a warm place until almost doubled in size (about 1 1/2 hours).
Punch down dough. Separate dough into 2 equal parts. Form 2 round, slightly flattened loaves. Score a 3/4 inch deep 'X" into the tops of both loaves with a sharp knife.
Grease (or spray) a large baking sheet; sprinkle with cornmeal. Put the loaves on top and then cover with a clean cloth and let rise until doubled - about an hour.
Preheat oven to 375 degress F. Bake 30-35 minutes or until crusts are dark brown and loaves sound hollow when tapped.
Remove from baking sheet and cool on a rack before slicing.