Preheat the oven to 160°C / 320°F / gas mark 3.
Heat 1 table spoon of oil in a deep casserole dish or Dutch oven until very hot and brown the meat on all sides. Do this in 2 to 3 batches heating more oil each time.
Use a slotted spoon or tongs to lift the meat out of the pot before setting it aside on a plate.
Add the onions and garlic cloves to the empty pot and sauté until lightly caramelised. Add more oil if necessary.
Sprinkle over 1 tablespoon flour mixed with 2 teaspoons of paprika and cook, stirring for 1 minute.
Add tomato purée, balsamic vinegar, mustard, red wine and stir.
Now add the stock and stir again before adding the carrots and beef. Pour the beef juices back into the pot too.
Season well with sea salt and freshly ground black pepper, put the lid on and place in the preheated oven for 1 hour.
Meanwhile, peel, wash and half the potatoes if necessary.
Bring a large saucepan of water to the boil and cook the potatoes until soft. Drain well and let cool slightly.
Use a ricer or masher to make a smooth mash.
Add butter, buttermilk, flour and lovage and mix well. Check seasoning.
After one hour, take the stew out of the oven, lift the lid and place leafy celery on top. Replace lid and put it back in the oven for 10 minutes, until the greens are wilted.
Meanwhile, form 12 round dumplings out of the potato mash mixture.
After 10 minutes, take the stew out of the oven again. Stir the celery in and place dumplings on top.
Put the stew back in the oven, and cook with no lid for further 20 to 30 minutes.
Before serving, sprinkle some freshly picked and chopped celery leaves on top.