Divide the goose from the dealer 5 large pieces, that is 2 breast halves with bones and wings, the two legs and the neck, lard and remaining bones also take.
At home, rinse the goose parts thoroughly with plenty of water, then boil the whole thing together with the washed and cleaned onions, celery and carrots (the whole thing cut into coarse pieces) in a saucepan with (with all the bones as well as the goose fat) so much water that the goose pieces are just covered. After the first boil, add the herb bundle, the peppercorns and a tiny bit of salt, then very lightly wallow the meat for 2 hours until it is very easy to separate the meat from the bones. Then cool the whole thing together in the saucepan, preferably overnight. The following day, skim off the fat (the defatted clear soup can be wonderfully frozen and/or used as a base for a delicious soup), and remove the meat from the bones and cut into not-too-small pieces.
Rinse and clean the Brussels sprouts, removing the outer leaves. On top, using a knife, cut the leaves small at the bottom of the stem and pick them off one by one. Blanch the Brussels sprouts leaves, that is, make them bubble in boiling hot salted water for 2 to 3 minutes, then pour them off on the spot through a sieve and rinse them with plenty of cold water.
For the meat breading, beat the egg thoroughly with a fork. Season the pieces of goose with salt