Remove the ends from the green beans and cut into pieces. Put in a saucepan with water, bring to a boil and boil for about 10 minutes, then pour into a colander to drain and set aside.
Put the black beans in a colander, rinse and drain. Put aside.
In the meantime, peel and finely dice the onion and garlic. In the case of the savory, pluck the leaves from the stems and cut finely. Core the chilli and dice finely (work with gloves if necessary).