In a large pot, heat the vegetable oil and sauté the onion until it is just beginning to caramelize. Add the curry paste and garlic, and fry for a minute, stirring often. Then add the peanuts and fry for another minute, again stirring well to prevent the mixture sticking.
Meanwhile, remove the base and the 3 hard outermost layers of the lemon grass stalk and thinly slice the remaining stalk until it gets too woody, but reserve the woody stalk.
Add the coconut milk, hot water, chillies, lemon grass slices and the reserved stalk, and bring to the boil. Add the butternut squash and the fish sauce, then simmer rapidly until the squash is almost cooked through. Add the peas and cook for a further 3 minutes, taste and adjust seasoning if necessary, then stir in the spinach and turn off the heat.
To make the cashew salad, simply mix the ingredients together.
Divide the curry between bowls, scatter a little of the salad over the top and let people help themselves to more as they wish.
© 2007 Peter Gordon. All rights reserved.