In a food processor combine all of the ingredients for the curry paste and blend until smooth.
For the curry:
In a wok over a high heat, warm the oil and add the lamb. Cook and stir for 5 to 6 minutes until browned on all sides. Stir in the curry paste and mix well to coat then allow to cook for 3 minutes, stirring continuously. Add the bay leaf, chopped tomato and coconut milk and cook covered at a simmer for 45 minutes.
Check the curry occasionally and give a good stir. Remove the cover and continue to cook for a further 15 to 25 minutes until the lamb is tender and the sauce is thick and creamy. Just prior to serving, remove the bay leaves then stir through two good handfuls of fresh spinach and cook until wilted. Serve immediately.