Braised lamb with a Mediterranean herb crust

Ingredients:

1 leg of lamb (approx. 2 kg)
4 cloves of garlic, finely chopped
4 sprigs of rosemary
4 sprigs of thyme
2 sprigs of oregano
2 onions, coarsely chopped
2 carrots, roughly chopped
2 stalks celery, roughly chopped
500 ml strong red wine
500 ml lamb or vegetable stock
2 tbsp tomato paste
2 tbsp olive oil
Salt and pepper to taste
Instructions: