Preheat your oven to 220°C/Fan 200°C/Gas 8. Strip the leaves off the cauliflower, then slice a sliver off the base so it sits up straight on your board. Slice roughly 2cm off the side (don’t worry if these bits crumble into florets), then slice the chunky middle bit into 2 thick steaks. Pop the cauliflower steaks and florets in a large roasting tin.
Peel the red onions and slice each one into 6-8 wedges. Add to the roasting tin, arranged around the cauliflower steaks.
Halve the chilli, flicking out the seeds and membrane for less heat. Finely chop the chilli and slide into a bowl. Grate in the lemon zest and stir in 1 tsp each turmeric, ground cumin and cinnamon. Pour in 1 tbsp oil and add a pinch of salt and pepper and mix well to combine.
Spoon the spice mix over the cauliflower and onion wedges and toss together till everything is well coated. Slide the veg into the oven and roast for 20 mins, till crispy around the edges and slightly charred.
Meanwhile, start making the warm houmous. Peel and crush or finely chop the garlic clove. Drain the chickpeas and rinse. Pour 1 tbsp oil into a pan and bring to a medium-low heat. Slide in the garlic and cook for 1 min, then add the chickpeas. Sprinkle in a generous pinch of salt and pepper and cook gently for 5-6 mins, stirring occasionally.
Strip the kale leaves from the thick stalks and tear the leaves into rough pieces. Discard the stalks. Scatter the leaves into a roasting tin. Pour over 1 tbsp oil and add a little salt and pepper. Scrunch the leaves to coat evenly with the oil, then slide onto the shelf below the cauliflower. Cook for 4-5 mins, till crispy around the edges.
Tip the chickpeas and garlic into a food processor. Spoon in 1 tbsp tahini and squeeze in the juice from the lemon. Whizz together, adding 3-4 tbsp water, till the houmous is smooth. Have a taste, and add more salt and pepper or water if needed.
Finely chop the parsley. Dollop generous spoonfuls of the houmous onto each plate and top with the roasted vegetables and leaves. Finish with a scattering of the chopped parsley.