Hi Julie C., here is the recipe (sorry for bad English)

1.5 kg Back of Lamb (is the filet with the bones)
Salt Pepper

Crust:
50 grams Butter
50 grams White Bread Crumbs
3-4 Garlic gloves (chopped)
2 Shallots (chopped)
3-4 Tbsp. mixed herbs (Basil, Thyme, Rosemary, Salbei(?), Parsley,) finely chopped
little bit of mustard
Salt and pepper

Lamb Stock:

Some Bones and Fat of Lamb (you'll get this from preparing the meat)
1 carot
1 stalk of celery
1 onion
2-3 tblsp. tomato paste
500 ml red whine
1.5 l water

Lamb Sauce

500 ml Lamb Stock (prepared as abouve)
200 ml Red Whine
2-3 Tblsp. Aceto Balsamico
Some Butter
Thyme
Rosemary

Prepare the lamb as follows: Put away all fat from back of lamb, and free the rib bones from meat as well as you can. (Save this for stock)
Season with salt and pepper
Heat some olive oil in pan, and brown meat all over.

For crust, melt butter in pan, lightly brown shallots, garlic, and herbs, mix into this the bread crumbs, let cool, and mix with mustard, salt and pepper
until mass is lightly wet but still firm.
With spatula or spoon cover lamb with mass. In preheated oven (150 degr. Celcius) let roast for approx. 40-45 min (it will then be lightly rose).
For serving, cut meat from bones in medallions.

Stock:
Heat butter in pan, fry meat and bones until brown, put diced veg. into pan, let roast, add tomato paste, roast, and add red whine. Let simmer a bit, then add water, and let simmer for 120 min. (discarding fat now and then with spoon).
Sieve through very fine sieve, and let again cook for 30 mins (then you should have 500 ml left)
Season (if necessary with salt, pepp.)

Sauce:
Reheat stock, add whine, balsamico, herbs and let simmer a while, sieve again, and finally add icecold pieces of butter for binding (do not cook anymore)

That's it - Sounds awfully lots of work, but is definitely worth it!!!
Enjoy, Martina