Peel and wash carrots and parsnips and cut them into pieces of about 4 cm. Clean and wash the celery and cut it into large slices. Wash thyme, shake dry. Peel onions, dice coarsely.
Dab meat dry and cut into cubes of about 5 cm.
Preheat oven (electric cooker: 150 °C/circulating air: 125 °C/gas: see manufacturer). Heat oil in a casserole or small roaster. Brown the meat all around in portions. Season with salt and pepper and remove.
Fry the vegetables and onions in hot frying fat. Stir in tomato paste and sweat briefly.
Deglaze with 1⁄2 l water and Guinness. Bring to the boil, stir in stock. Add meat and thyme. Cover and braise in the hot oven on the lower shelf for about 3 hours. Season to taste with salt and pepper.
It goes well with mashed potatoes.