Preheat oven (electric cooker: 200 °C/circulating air: 175 °C/gas: level 3). Wash the meat, dab dry and cut the rind (see tip). Season with sea salt and pepper. Place in the fat pan of the oven.
Roast in hot oven 1 1⁄2-1 3⁄4 for hours.
Clean, wash and coarsely chop the soup greens. After approx. 10 minutes spread around the roast. After 15 minutes gradually add 3⁄8-1⁄2 l water. After approx. 1 hour roasting time, switch the temperature up (electric oven: 225 °C/circulating air: 200 °C/gas: level 4) or switch on the oven grill for the last 10 minutes so that the rind throws bubbles and becomes crispy.
In the meantime peel, wash and cut the potatoes into pieces. Cover and cook in salted water for about 20 minutes.
Clean, wash and cut the beans into pieces. Peel and chop the onion. Fry in 1 tablespoon butter until translucent. Add the beans and 1⁄4 l water and steam covered for about 5 minutes. Season to taste with salt.
Remove the roast. Place the roast stock and vegetables in a fine sieve, collecting the stock in a pot and degreasing it. Pass the vegetables through the sieve to the sauce. Keep the roast warm on the fat pan.
Stir the cream into the stock, bring to the boil briefly. If the sauce is too liquid, stir the starch with 2 tablespoons of water until smooth and stir into the boiling sauce. Season to taste with salt and pepper.
Drain the potatoes. Add milk and 1 tablespoon butter. Mash finely with a potato masher. Season with salt. Cut the roast open. Arrange everything.