Preheat the oven to 200C (180C fan, 400F). In a large bowl, add the harissa, yogurt, 1 tbsp oil and a pinch of salt and pepper. Mix well.
Pop a cauliflower head top down into the bowl and rotate until well covered on all sides.
Spread the remaining oil on a large non-stick baking tray large enough to accommodate your cauliflowers. Place the cauliflower heads, stalk side down on the tray and place in the oven to roast for 30 minutes.
Remove from the oven and brush on any remaining harissa yogurt.
Turn the heat up to 220C (200C fan, 425F), return to the oven and roast for a final 15-25 minutes until the crust is set and considerably deeper in colour.
When your cauliflowers are close to completing their second stint in the oven, it's time to prepare your side dishes.
To make the wilted greens
Warm the olive oil in a pan over a medium heat.
Add the garlic, spring greens and kale with a pinch of salt and pepper. Fry gently 2-3 minutes until hot and glossy.
Turn off the heat and put the lid on the pan to wilt until you're ready to serve.
To make the lemon tahini sauce
Mix the tahini, lemon juice, garlic, parsley, salt and pepper in a small bowl.
Add the yogurt and honey and mix again.
Taste to check the seasoning, then cover until ready to serve.
To make the herby couscous
Put the couscous, apricot pieces, parsley and a crumbled stock cube in a heatproof bowl.
Add the boiling water and mix well then cover and leave for 5 minutes.
Once your cauliflowers are fully roasted, leave them to cool and firm up for 10 minutes, then cut into wedges.
Fluff up the couscous with a fork, then serve a large spoonful to each plate. Add 2-3 wedges of cauliflower and the wilted greens.