1. Cut the stem of the lemongrass into halves and crush the halves under a pan or with a knife.
  2. Fry the onion for 3 minutes in a few tablespoons of oil in a Bourgogne casserole.
  3. Add the garlic, lemongrass, ginger and chilli and fry for a minute.
  4. Pour the coconut milk and fish sauce into the pan.
  5. Add the sugar and bring the dish to the boil.
  6. Stir briefly so that the sugar dissolves.
  7. Add the aubergine and let it simmer for 5 minutes on low heat with a lid on the pan.
  8. Add the broccolini and let it simmer gently in the dish for 5 minutes.
  9. Add the prawns, stir and let it simmer for another 5 minutes until cooked.

Serve in bowls and sprinkle with roasted sesame seeds.