Bring the chicken stock to the boil, add the peas and boil gently until very tender (about 20 minutes); put them through a mouli-legumes (vegetable mill) or allow the liquid and peas to cool a little and then process in the blender in several batches.

Peel and dice the potatoes; peel the onion and chop very finely. Shred the well washed and dried curly endive leaves into a chiffonade.

Sweat the onion and endive in the butter and oil in a large saucepan until tender; add the potatoes and fry briefly, stirring.

Pour in the pureed peas and stock, add salt to taste and the saffron. Simmer for 10 minutes.

Season with a little freshly ground pepper and serve.