The most difficult part of making the marbled rye bread was finding caramel color to make the dark rye dark. As in a pumpernickel bread you can also use unsweetened chocolate or coffee, but as this bread is quite light in flavor, I suspect those are a little more likely to come through in the taste profile. After googling turned up a hint in posts for the first-round BBA Challenge ("try Asian groceries"), I made one pass at the DeKalb Farmer's Market before trying the high-percentage shot of the Buford Highway Farmer's Market. Sure enough, after writing out my question for the Eastern European woman at Customer Service when her English comprehension couldn't figure out how to search the database (her spoken English was quite good, though), she determined that I could find caramel coloring in the Korean grocery section. The Vietnamese CS person directed me to, well, not the right aisle, but close, and after several passes through 3 different nationalities' grocery, soft drink, and other foodstuffs I finally spotted the bottle labelled "caramel coloring". Ingredients: molasses, water. I am a little leery of the translated ingredients stickers on these small-scale imports, and I must say it didn't taste exactly like molasses. It worked for the dark rye, though!
That hurdle over, the marbled rye was basically 2 batches of light rye bread, one with caramel coloring added. I made a half-recipe, and added the optional caraway seeds. I went with the "four slab" method of getting a marbled pattern with pretty good success--one end was more bull's eye than swirl, but in the middle of the loaf I got a nice swirl pattern. I think if I flattened my slabs a little more and worked on a tighter roll (trying to get a full rotation of the doughs) I could get a consistent swirl end-to-end. The bread nicely filled my bigger loaf pan.
Tasting results: it's a light-textured rye with a pretty light rye flavor, too. I prefer a rye with a little more chew and a little stronger rye character, but this is certainly a very acceptable rye sandwich loaf. It made for very nice grilled cheese sandwiches with some leftover asiago and aged provolone cheese last weekend.