Preheat the oven to 190°C.
Peel the beetroot and squash, then cut them into bite-sized chunk. Peel and cut the onion into wedges. Cut the red pepper into chunks.
Put the veggies in a large baking tray, then pour over the oil, season with salt and pepper, dust with the spices, then toss well and roast for 20 minutes.
Meanwhile, mix the passata with the garlic. Add a couple of pinches of chilli flakes, if you’d like it a bit spicy. Season with salt and pepper to your liking.
After 20 minutes of roasting, take the tin out of the oven and toss the vegetables. Pour over the passata mixture and toss again.
Roast for another 10-15 minutes, then take it out of the oven and let it cool.
Transfer the whole content into a liquidizer and add the fresh coriander leaves. Whiz until you get a thick, silky sauce.
Transfer the sauce into a jar, store it in the fridge and use it within three days. (Or freeze it, divided into small portions)