Heat the oven to 220°C / 200°C fan assisted/450F/Gas mark 7
Put the cauliflower florets into the roasting dish, season them well, scatter some cayenne pepper over, put 1 tbsp olive/coconut oil over and toss. Cook for about 15 mins till golden on edges then add the peeled onions (cut in chunks) and cook for a further 12 mins.
While veggies are still cooking in the oven, peel and crush the garlic - chop finely along with the chilli (remove nervures inside the chilli as it might be too spicy otherwise).
Pick up your soup pan and put over heat, add the remaining olive/coconut oil, put the cinnamon stick, garlic and chilli in. Stir in for a minute or so and then add the Passata with the whole amount of water (500 ml) preferably boiling. Bring to boiling and then lower the heat and allow to simmer for about 10 mins until it slightly thickens.
Remove the cinnamon stick and add the baked vegetables (cauliflower + onions).
Season with salt and pepper to taste, give it a whizz if you don't prefer chunks.
Dish up into bowls and serve with dukkah/cumin/coriander powder scattered on top, or with some nice parsley leaves.