Heat the oil in a large sauté pan over a medium heat. Add the mustard seeds and cook until they start to pop. Add the chilli, cumin, turmeric, ginger and garlic and cook for 30 seconds. Add the beans, a splash of water and a good pinch of salt. Cook for 3–4 minutes until just tender, stirring frequently and adding a little more water if necessary.
Serve hot or warm.