Place the flour in a large bowl and season with salt and pepper. Add the meat and toss to coat.
Heat the oil in a large lidded pan until hot. Add the meat in batches and cook for 2-3 minutes, turning occasionally until brown on all sides. Remove from the pan and repeat until all the meat is browned. Reheat the pan add the onion and mushrooms and cook for around 5 minutes until softened and beginning to brown. Remove from the pan.
Dissolve the stock cube in a litre of boiling water and add to the pan with the beef, cover and simmer gently for an hour or until the meat is tender. Add the tomatoes, potatoes, carrots and herbs along with the cooked onion and mushrooms and simmer for another 20 minutes.
Whilst the vegetables are cooking make the dumplings. Mix the ingredients together in a bowl and gradually add 3-4 tbsp cold water to bring the dough together. Divide into 6 and shape into balls.
Add the dumplings to the top of the casserole, cover and cook for a further 20 minutes until they are soft and risen and the vegetables are tender.