Make the coconut sauce. Put the tamarind in a bowl. Pour over the measurement water and leave to soak for 30 minutes. Mash the tamarind in the water, then push through a sieve set over another bowl, squashing the tamarind so that you get as much of the pulp as possible; discard the stringy bits and any seeds.
Take 2 tablespoons of the cream from the top of the coconut milk and pour it into a wok or large frying pan. Add the curry paste, ginger, onion and turmeric, and cook over a gentle heat, stirring, for 2–3 minutes. Stir in the rest of the coconut milk and the tamarind water. Bring to the boil, then reduce the heat to a simmer and add a pinch of salt.
Add the broccoli to the coconut sauce and cook for 5 minutes, then add the green beans and red pepper. Cook, stirring, for another 5 minutes. Finally, stir in the courgettes and cook gently for 1–2 minutes until the courgette is just tender. Serve immediately with some crispy prawn crackers.