Heat the oil in a large, heavy-based saucepan and cook the onion and lamb over a moderate heat for 4–5 minutes until golden and soft. Add the leek, apricots and new potatoes and cook for 2 minutes, then add the thyme and flour and stir well to coat lightly. Pour in the stock, then bring to the boil and cover and simmer gently for 35 minutes, stirring occasionally.
Meanwhile, make the dumplings. Place the flour and salt in a bowl with the thyme leaves and suet and mix well. Mix in enough water to make an elastic dough. Divide into 12 and shape into small walnut-sized balls using lightly floured hands. Stir the hotpot and top up with a little water if necessary, then drop the dumplings into the stock and cover and simmer for 15 minutes until the dumplings have almost doubled in size.
Serve the hotpot ladled into warm serving bowls with the dumplings.