Preheat the oven to 150°C (gas 2). Toss the cubes of beef in the flour, seasoned with a little salt and pepper. Heat 2 tbsp of the oil in a large heavy-based frying pan and brown the meat in batches over a high heat, turning frequently. Transfer to a large flameproof casserole, using a draining spoon. Place the bay leaves on top of the meat.
Add the remaining 1 tbsp of oil to the frying pan and gently cook the onion for 10 minutes until soft and translucent. Add the garlic, root vegetables and celery and cook for a further 2–3 minutes or until just starting to colour. Add to the casserole.
De-glaze the pan by pouring in a little of the stock. Bring to the boil, scraping up any crusty bits from the bottom of the pan, then stir in the tomato purée, vinegar, redcurrant jelly and herbs. When blended, pour over the vegetables, then add the remaining stock.
Bring the casserole to the boil, then cover tightly and cook in the oven for 2 hours or until the beef and vegetables are tender. Turn up the oven temperature to 160°C (gas 3).
To make the dumplings, sift the flour with the mustard, if using, and a pinch of salt into a mixing bowl. Stir in the suet and rosemary, then add about 100ml cold water to make a soft, but not sticky dough. Divide into twelve equal pieces and lightly roll into balls with floured hands.
Remove the casserole from the oven after 2 hours and arrange the dumplings on top. (It is important that the liquid is hot and bubbling when the dumplings are added, to ensure that they rise well.) Cover again and cook in the oven for about 20 minutes or until the dumplings are well risen, light and fluffy. Serve straight away on warmed plates.
*Some red wine, stout or pale ale can be used to replace part of the stock. *Redcurrant jelly adds a subtle taste and shine to the sauce, but is not essential. You can use 1/2 tsp sugar instead. *The stew is suitable for freezing without the dumplings. Use within 3 months. Thaw in the fridge, then reheat gently.