Cut the onion into long strips. Halve the courgette twice lengthways and cut into bite-sized pieces.
Remove the stalks from the tomatoes and dice the tomatoes. Peel and grate the ginger and finely chop the garlic. Heat the oil in a pan and add the mustard seeds and cumin. When they sizzle, add the onions and sauté for 3 minutes. Add the garlic and ginger and fry briefly, then add the spices, fry briefly and deglaze with the tomatoes. Fry everything at a high temperature for several minutes, then deglaze with water. Add salt and fresh chilli pepper as required. Simmer for approx. 20 minutes until the courgettes are soft.
Serve garnished with herbs.