Add ready-cooked, stir-fry noodles with the prawns and spinach. Or replace the prawns with 2 peeled sweet potatoes.
Open the coconut milk, pour the thin milk into a jug, keeping back any thick coconut cream. Scoop the coconut cream into a blender. Add 2-3 tbsp of the coconut milk plus curry paste, sugar and coriander stalks and blend to a smooth paste. Heat a wok, tip in the paste, stir fry for 1-2 mins, then pour in the remaining milk from the jug.
Bring to a simmer, then add the prawns and spinach. Cook until the prawns are heated through and spinach has wilted. Add lime juice and fish sauce, then spoon into bowls. Scatter over coriander leaves and serve with plain rice or noodles.