Rub the shoulder with oil and salt. Clean the vegetables and chop them roughly.
Now mix the vegetables with the tomato paste, put them in a roasting pan, put the shoulder on top and let them roast for about 20 minutes, until the shoulder and the vegetables have got some color. Then add the remaining ingredients and put the lid on. Turn back the oven and let everything simmer at 120 degrees for about 3 hours.
When you have finished the sauce (strain the vegetables and reduce or thicken the sauce, season to taste), you can leave the shoulder in the oven on the wire rack.
It goes well with fried Chinese cabbage and mashed potatoes