Anglo-Indian lamb pot roast

Wash the meat.
Cut incisions diagonally across the joint and insert the garlic, ginger, cloves, allspice and peppercorns into the incisions.
Smear the meat with the butter, then sprinkle with paprika, salt and pepper.
Squeeze the lemon juice over the meat, cover and set aside in the fridge to marinate for at least 2 hours, but preferably overnight.
Heat the oil in a large saucepan. Once hot, brown the meat.
Add the onion and tomato, cut side down.
Add a little water, then cover with a tight-fitting lid and cook over a low heat for 1 hour.
Check every now and then and add more water if necessary.
Add the potatoes and cook for a further 30 to 45 minutes, until meat and potatoes are tender.