See Guy's French bus bean stew here.
Soak for 8 hours or overnight in a large bowl with twice the volume of water, or if you don’t have as much time, hot soak them. Put the beans in a large saucepan with twice the volume of water and bring to the boil. Boil for 2 mins, remove from the heat and leave to soak in the pan for 1 hour.
Drain and rinse well in cold water.
Boil rapidly in plenty of water for 10 mins, then simmer for 1½-2 hours, on their own or in your choice of recipe.
For a richer flavour try adding a bulb of garlic cut in half across the cloves, rosemary or thyme, black peppercorns, a bay leaf, a few sticks of celery, onions or shallots... You can also add stock bones or boil them in chicken stock. Avoid overcooking as coco haricot beans have a habit of disintegrating (an advantage if making as a hearty stew). After cooking, you can keep any excess water to make into a tasty stock.
9 months in dark dry conditions.