Franconian Sauerbraten
To marinate ~1kg of beef you’ll need approximately
½ tbsp salt
1 tbsp sugar
¼ tsp cinnamon
3 small onions
1 bay leave
2 dried cloves
5 dried juniper berries
5 dried allspice berries
3 peppercorns
1 tsp mustard seeds
100 ml white wine vinegar
(Or you cheat like I do and buy a pre-made mixture, adding only the ingredients that are missing. I don’t keep allspice, juniper berries or mustard seeds around, as I have little use for them otherwise)
Place the meat into a small pot or container with lid, fill it with water until the meat is submerged, then add in the ingredients for the marinade, stir, close the lid and keep it in the fridge for a couple of days at least. (Since we mostly shop Saturday, it’ll sit for a week in my case, but 2 - 3 days should suffice according to the recipe).
To cook, remove the meat from the marinade and pat it dry. Heat up the marinade, sprinkle the meat with salt and pepper, then sauté and add in part of the marinade and spices until it’s mostly covered. I use a cast iron pot with a heavy lid to cook it on low heat for 2 hours (turning it once after an hour). If you use a lighter pot where the liquid might eventually evaporate, make sure to top up the marinade occasionally.
When it’s nearly done, I prepare the sauce in a separate pot. Start with a dark roux, then add in liquid from the pot with the meat, filtered through a sieve. I also add some cream. If it’s still too sour, some sugar or a bit of water will soften it. If it’s not sour enough, add more marinade. You probably don’t want it as sour as a sweet-and-sour dish at a Chinese restaurant, though.
As for possible sides: dumplings might be a fit (that’s likely the combo you’ll find in a Bavarian restaurant), or perhaps potatoes. For me, I cannot imagine eating anything other than long, hollow pasta with it 
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