Cut the monkfish into 3 cm (1¼ inch) cubes. Using a large knife, slice each lemon grass stalk in half lengthways. (If the stalks are very thick, pull off the outer layers, finely chop them and add to the oil with the chilli flakes.) Cut the thin ends of each stalk to a point and thread the monkfish on to the skewers. If it is difficult to thread the fish, pierce each piece with a small knife first to make threading easier.
Finely chop the spring onions, keeping the white and green parts separate.
Heat the oil in a large frying pan with the chilli flakes, garlic and white parts of the spring onions. Add the monkfish skewers and fry gently for about 5 minutes, turning once, until cooked through. Drain to a plate.
Add the rice, coconut milk and creamed coconut to the frying pan and bring to the boil. Reduce the heat, cover with a lid or foil and cook gently for 6–8 minutes, stirring frequently, until the rice is almost tender and the milk absorbed. Add the measurement water and cook, covered, for a further 10 minutes until the rice is completely tender, adding a little more water if the mixture boils dry before the rice is tender.
Stir in the vinegar, remaining spring onions and then the spinach, turning it in the rice until wilted. Arrange the skewers over the rice. Cover and cook gently for 3 minutes, then serve immediately.