Put the cumin and coriander seeds in a dry pan and toast until fragrant. Grind to a fine powder in a pestle and mortar.
Put the shallots, lemongrass, chilli, garlic, galangal, lime zest, salt, coriander roots, cumin and coriander into a blender with 400 ml of coconut milk and blitz to a fine, wet paste.
Pour the paste into a large wok or saucepan and fry over a high heat. It will spit a bit at first so keep stirring. It will start to settle and thicken up and the oil will start to seperate from the paste. The colour will change to a deeper green colour.
Chuck in the globe and pea aubergines, the rest of the coconut milk, the water and the sugar and cook on high for 4-5 minutes.
Chuck in the squash and cook for another 4-5 minutes. Check for seasoning, adding a bit more salt/sugar if needed. Turn off the heat and throw in the Thai basil, saving a few leaves for garnish.
Serve in bowls topped with fresh red chilli and some more basil. This goes perfectly with either steamed rice or rice noodles.