Peel the squash, remove the seeds, then cut into 2-3cm cubes.
Heat the oil in a large saucepan and gently fry the chopped onions and garlic for about 5 minutes, then add the ginger, chilli, bay leaf and squash pieces. Fry for another 3 minutes while stirring.
Pour in the vegetable stock, bring to a boil, then under cover simmer for 25 minutes at low temperature.
When the squash is soft, turn off the heat, let it cool for a couple of minutes. Discard the bay leaf and add the coriander and blend the soup. Taste it, add salt and pepper if needed. Reheat it before serving.
Serve the soup with creamy yogurt and crusty bread if you like.