Melt 2 soup spoons of butter in a saucepan and partially cook the meat in it. Add the onions, and let them cook with the meat for 3 minutes. Now add the tomato, garlic, salt, thyme and water. Cover and cook for 20 to 25 minutes.

While the meat is cooking, boil the potatoes in their skins for 25 to 30 minutes. Peel and cut them into thick slices, then saute them in a frying pan in a tablespoon of butter.

Place the meat on a platter, sprinkle with chopped parsley and surround it with the sauteed potatoes.