For the stew, heat the olive oil in a large frying pan and lightly cook the lamb until browned on both sides. Transfer to a large saucepan.
Add the chicken stock, vegetables and herbs to the saucepan.
Bring slowly to a simmer and cook for about 1½ hours or until the lamb is tender and falls from the bone.
Remove the vegetables and herbs from the stock and discard them. Reserve the stock for cooking the dumplings and vegetables.
For the dumplings, blanch the spinach in boiling water for 30 seconds, then plunge into iced water. Drain and squeeze until thoroughly dried. Finely chop the blanched spinach.
In a mixing bowl set over a pan of boiling water, beat the ricotta until smooth. Gradually add the egg yolk and then the parmesan. Remove from the heat and stir in the flour to make a dough.
Fold in the spinach, before rolling the dough into balls the size of a walnut.
Heat the lamb stock in a medium saucepan. Drop in the dumplings and cook for 5-8 minutes until cooked through - you will know they are done when they float to the top of the pan.
Meanwhile, heat the lamb stock for the vegetables in a medium saucepan. Add all the vegetables, except the tomatoes, and cook until softened, but still retaining bite - this should take about six minutes. Drain the vegetables, reserving the stock.
Blanch the tomatoes by scoring them with a sharp knife, dropping them into boiling water and leaving for 5-8 seconds. Transfer to a bowl of cold water. Using a sharp knife, carefully remove the skin.
Add enough of the lamb stock to the stew to bring it to sauce consistency. Serve the lamb topped with the cooked vegetables, blanched tomatoes and dumplings.