Preheat the oven to 200C/400F gas mark 6. Arrange the red onion on a large baking tray, drizzle on ½ tsp of oil, sprinkle with salt and pepper and place in the oven for 10 minutes.
Mix together the Asian-style sauce ingredients in a small bowl and put to one side.
Remove the tray with the onions on, from the oven, and add the broccoli, mushrooms, courgette, peppers and asparagus. Arrange in a single layer and drizzle on the remaining olive oil. Sprinkle on a pinch of salt and pepper and place back in the oven for 10 minutes.
Remove the tray from the oven and drizzle the Asian-style sauce over the vegetables. Toss everything together, then sprinkle on the cashews and sliced chilli.
Place back in the oven for a final 5-10 minutes until the sauce is bubbling and the vegetables are tender.
Serve with coriander-flecked boiled rice.
Can I make it gluten free? Yes! Replace the soy sauce with tamari. The other sauce ingredients, such as sweet chilli sauce and lemongrass paste are usually gluten free, but it's best to check the specific brand.
Can I make it ahead? Yes, you can prepare in the morning or the night before by chopping the veggies and placing them on the tray in advance, covered. The recipe calls for the onions to be cooked on their own for 10 minutes first, but if you chop them smaller, you can add them with the rest of the veg. You can also mix up the sauce in advance and cover. So it's just a case of baking and drizzling come tea time.
What about leftovers? Quickly cool, cover and refrigerate leftovers. They taste great cold the next day as part of a salad with some cous cous. You can reheat them, covered, in the oven at 170C/325F for around 10 minutes if you like, but the vegetables will be softer after reheating.
Will it freeze? It freezes ok, but the vegetables are a lot softer once defrosted and reheated. If I freeze any leftovers, I just use them to add into rice or a stir fry as an added extra, rather than a meal in itself.
.Nutritional information is per serving, excluding the serving suggestion of rice and coriander (cilantro).