To prepare the meatballs:
Soak the bread crumbs in the milk for 10 minutes.
Add the ground lamb (or beef), the oregano, nutmeg, beaten egg, salt, pepper and Worcestershire sauce.
Mix well and form into 1 1/2 inch balls. Fry the meatballs in in a olive oil to brown on all sides. Remove meatballs to a covered, put into slow cooker.
To the same frying pan add the diced carrot, celery, garlic and red onion. Sauté together until the onions soften, then add this mixture to the slow cooker with the meatballs along with all the remaining ingredients.
Cook low 6 - 8 hours, or high 3 - 4 hours