Wash the roast, dry it and rub the underside with salt. Cut into the rind like a grid (I always have this done by the butcher I trust), place the meat with the rind facing up on the wire rack of the water-rinsed griddle and put it in the oven.
As soon as the dripping roasting is browning, pour some water into the griddle. Put the peeled onion, cut into quarters, and the washed, cut tomato in the griddle 15 minutes before the end of the roasting time.
When the roast is done, dissolve the roast set with 250 ml water, place in a saucepan, add canned milk and heat. Mix the cornstarch with the water and bind the sauce with it.
I also have napkin dumplings (prepared in the water bath form). Seasonal vegetables or salad also go well with it.