Heat oven to 220C/200C fan/gas 7. Toss the pumpkin in the oil, then sprinkle on the chilli powder, five-spice, 1 tsp black pepper and a pinch of salt, and mix well. Tip into a roasting tray in a single layer and cook for 25-30 mins until tender and starting to caramelise around the edges.
About 5 mins before the pumpkin is cooked, heat a wok or large frying pan and add the green beans plus 1-2 tbsp water. Cook for 2-3 mins, then add the bok choi, soy, vinegar and syrupy, and cook for a further 2-3 mins until the veg is tender. Add the lime juice, then divide between 2 plates with the pumpkin, coriander leaves and lime wedges.