Savoy cabbage and coriander soup

This is inspired by a recipe by Denis Cotter.  We recently had a couple to stay who were driving their uni-mog down africa and they were my guinea pigs needless to say this was a firm favourite of theirs!
4 large onions
1/2 a savoy cabbage
olive oil
2 red chillies, finely chopped
4 cloves of garlic, finely chopped
1 large piece of fresh root ginger-peeled and chopped
2 tabespoons coriander seeds-crushed
about 800ml of good veg stock
400 ml tin of coconut milk
A large bunch of fresh coriander-chopped
juice of one lemon-or 3 limes
salt and black pepper

Finely chop onions and shred cabbage-we do ours by hand but you can use a slicing disc on a food processor.
Heat a good splash of olive oil in the pan, add the onion and cabbage, cook over a moderate heat for a couple of minutes before adding the chillies, garlic, ginger and coriander seeds.  Continue cooking for about five minutes, stirring regularly, until the cabbage is tender.  Add the stock-simmer for about five minutes then add the coconut milk, half of the fresh coriander, the lemon/lime juice and salt and pepper.  Simmer for a few more minutes.

Serve the soup with the rest of the fresh coriander.