Heat the oil in the casserole dish
Sauté all the ingredients, except the celery leaves, beans, tomato puree, salt, stock cube and 2 of the thinly sliced spring onions
Add the water, salt and the stock cube
Cook for 30 minutes over a low heat
Add the beans, celery leaves (snipped) and reserved spring onions 5 minutes before the end of cooking
Serve
