We peel the potatoes, rinse, drain and cut them in chunks.
Preheat the over to 370oF.
Rinse the lamb chunks, drain and put them in a Dutch oven. We add the "Santorini" tomatoes, grated tomatoes, potatoes, onion, garlic, olive oil, salt and pepper to taste and mix.
Then we add to the Dutch oven enough water to cover the ingredients. Put the lid on and bake in the preheated oven for 40 minutes.
Take the lid off and continue baking for an additional 20-25 more minutes, until both lamb and potatoes are tender and browned. We may add some more boiling water if needed.
Remove the Dutch oven from the oven and serve the "Arnaki Kokinisto Sto Fourno"