Place the venison, red wine, rosemary, peppercorns and bay leaves in a large bowl. Leave in the refrigerator to marinate for several hours, preferably overnight.
Heat 1 tablespoon of vegetable oil in a large pot and sauté onion until translucent.
Meanwhile, remove venison from the marinade, retaining the marinade for later use. Pat the meat dry with kitchen paper. Mix together the flour, salt and pepper and coat venison with the mixture.
Preheat oven to 140 degrees C.
Remove onions from the pot. Add the venison and brown in small batches (about 6 cubes at a time). Add more oil or a knob of butter if necessary. Once meat is browned, put all of the meat and onions into a casserole dish and add the chopped carrots. Pour the reserved marinade over the meat and vegetables.
Put the lid on the casserole and cook in the preheated oven for 3 to 4 hours. The casserole is ready when the meat is tender and falls apart with a fork.