In a large saucepan, heat a little oil. Add the pieces of beef and fry quickly until coloured or sealed all over.
Add the vegetables, stir, and continue to sear for a further 3-4 minutes until all the vegetables are well coloured.
Next, add the tomato puree and a spoon of mustard if desired. Stir to coat and colour for a few seconds up to a minute.
Pour in the stock and red wine. Bring to the boil, then reduce the heat to low and simmer over a gentle heat for 2.5hours to 3 hours, covered with a tight-fitting lid until the meat is tender.
Meanwhile, prepare the dumpling. Mix the self-rising flour, salt, shallot, Dijon mustard, chestnut and fresh parsley together. Mix well.
Slowly pour and stir in the buttermilk until the dough comes together. With a knife, a pastry cutter or simply with your hands create or cut out the dumplings. They should be not bigger than a golf ball. Leave them to set in the fridge until required.
About ½ hour before the stew is ready to serve, drop in the dumplings. Leave them to cook in the stew for about 25-30 minutes until plump with the cooking juices and oozing of flavour.
Serve while piping hot.
