Graubrot

 Hi a quick internet search and I found several, which I've listed below.  Only the first two links below employ a sourdough technique, but I included the others so that you could compare what might be other ingredient combinations.  They vary considerably, and the accompanying description to one of them says that the formula varies by region within Germany.  It looks like you may have to experiment to discover which is your fiance's preference.    

Sourdough:

http://germanfood.about.com/od/allbreadrecipes/r/rye_graubrot.htm

http://groups.google.com/group/alt.bread.recipes/tree/browse_frm/month/1999-11/a1c773e507b7ddab?rnum=71&_done=%2Fgroup%2Falt.bread.recipes%2Fbrowse_frm%2Fmonth%2F1999-11%3F#doc_ee421dc1e8ec8597

Non-sourdoug:

http://recipes.wuzzle.org/index.php/55/1220

http://www.food.com/recipe/german-style-grey-bread-rye-wheat-mix-graubrot-436844

the first one at http://germanfood.about.com/od/allbreadrecipes/r/rye_graubrot.htm gives it in grams.

Basically, it looks like this is a 30% rye bread. I have a 35% recipe that is my most popular hearth loaf and it's very simple: 35% Rye, 65% White (organic stone ground/organic all purpose), 1.8% Portuguese Sea Salt, 65% hydration. Personally, I like a slow process so begin by soaking the flour whilst building up the starter to about 4% of flour weight in the morning in summer months, 6% in winter months, then mixing in the starter with the soaked dough in the evening, retarding it overnight in the fridge, then shaping it around 9 am an baking it around 1 pm, but if that sort of schedule is far too slow and cumbersome, you can tweak the timing by increasing/decreasing starter percent, eliminating the soaking period and so forth.

Generally, I find it's best to take an initial amount of starter and then 'build it up' to the amount you need for the recipe so that what goes into the recipe is relatively fresh, young starter populations. Personally I use a 33% rule, i.e. if I want to end up with 100g starter, I begin with 33g mother (half water half flour, i.e. 100% hydration though other percentages would work), 33g new flour (preferably fresh ground rye kernels), 33g water and give it 6-12 hours, until you have a nice and tart rye sponge which is then added into the dough with salt, caraway seeds etc.

Here is the recipe for 2 loaves:

Starter 43g  (4.5% flour weight)

Total Flour  939

Flour not counting starter 918g

Water  611

Water not counting starter water  589

Salt at 1.8% of flour  17g

Caraway Seeds  at 0.3% of flour 3g.

Phase One: Build up Starter to 43 g with 15g mother, 14g water, 14g Rye flour for 6-12 hours until a nice tart still rising  ( not collapsing) sponge (Say 10 am in this example). Option One Premix: mix flour, salt, caraway, water together now (though some doing this would hold back on salt until starter goes in later).

Phase Two: Option One: add starter to premix from Phase One, or Option Two: now mix everything together. Both Options: give overnight/8hours plus fermentation time, either in fridge or at room temp. (Say 8 pm this example). Do a couple of stretch and folds after mixing just to ensure there are some nice long-formed gluten strands. Time will do the rest, you are just getting those gluten strands off to a good start and that's all. If using mechanical mixer just mix until water and flour are mutually incorporated, no further, at slowest speeds possible. The less manipulation the better.

Several hours (3-5) before baking, shape and proof (Say 9 am this example). Be warned this can be a sticky dough, also it will tend to get over-ready in warm temperatures all of a sudden at the end as the fermentation cultures hit fast-doubling population mass. Use oiled loaf pans or well oiled and floured bannettons to hold shape. Dough is just right for baking when it gets to the just-getting-puffy phase but not 'it has already fluffy'd out' phase (!). All-purpose flour or high protein/gluten bread flour will counteract the squishy flattening tendencies of rye flour to give a great rise. Lower protein and/or stone ground whites will not give as much rise but will yield richer flavours and provoke more German gratitude as well as possibly more children as a result!

Bake between 400 and 700F (higher temps for radiant heat / brick ovens only). (Say 1 pm this example.) Using techniques like baking in pot, steam, high temps etc. also help.

If you want shorter fermentation times, increase initial starter percent. The longer the prep and fermentation period, the richer and more subtly variegated the flavours (assuming using good flour).

Quality of flour makes a huge difference in flavour and quality of fermentation populations, and since they use good quality stuff in Germany and he clearly cares about his bread, only use high quality organic grains and flours.

(Also encourage him to learn how to make the bread himself! He knows what he is shooting for. And at a pinch during tough times, he like me could turn it into a second career! There is a definite demand for high quality German-style sourdoughs!!)

Viele Gluck!

This is easier to do only if you have your own grinder, like a Nutrimill. If you have a German fiance who likes good bread, it could be a very good purchase (about $300.00 and 7 year guarantee).

To make a Rye Vollkorn brot, basically it's the same as above with a couple of wrinkles:

2 700g baked loaves:

Starter: 30g  (10g mother, 10g water, 10g fresh ground rye)

Premix: (this MUST be mixed at first to give whole grains time to process, i.e. it's not an 'option'.)

Rye  814g  (100% flour)

Water 656 g (81% flour)

Sea Salt 15 g  (1.8% flour)

Spices: Coriander, Fennel Seed, Anise Seed, Caraway, ground with flour: 1.2 g each (0.2% flour)

Seeds: Sunflower and Ground flax (these are optional of course but are factored into finished loaf weight):41g (20.5g each) PLUS 41g water.

Method Narrative:

Phase One: Starter Build and Premix

In one bowl get the starter going for 7 + hours until a nice, tart, not collapsing sponge

In another bowl premix flour, water, salt, seeds, spices. (Option to hold back on salt until starter is added in later).

Phase Two: Fermentation

Combine everything, mix well, no kneading or stretching. Then ferment for about 12 hours.

Proofing, Baking etc.

Put into loaf pans 4 hours before baking. Option: put into loaf pans (large size) in Phase Two.

Then Bake at not more then 450, 400 is better. You do not want overly hot oven since crust will become way too hard. Slow, gentle baking is best with this loaf, also much steam but it doesn't matter too much since dough is so moist.

After it is done to 195% in the centre (don't overdo it again because otherwise crust is too hard), let cure for 24 hours ideally.

Tip on grinding: Grind most of the flour at just above the Fine setting on the Nutrimill (don't know about other mills) but then about a third on the Middle and/or Coarse setting. But don't grind it all on Coarse setting, the dough will bake overly compacted and dense. A fine setting yields a delicious loaf with a satisfying nutty, granular texture. This is a truly superior loaf and very easy to make once you have done it a couple of times.