Wash the lemon well, grate the peel and squeeze the juice.
Mix garlic, lemon zest and juice, spices, harissa, tomato paste and oil in a bowl.
Rub the cauliflower all over with the spice paste. It's best to wear disposable gloves for this. Also smear some paste into the spaces between the stalks so that the cauliflower is nice and spicy.
Place seasoned cauliflower on a baking sheet or in a baking dish and roast in the oven for about 30-45 minutes (depending on size).
Tahini yogurt sauce
Peel and finely chop or grate the garlic.
Mix yogurt in a bowl with garlic, tahini, water, lemon juice and honey. Season to taste with salt and pepper.
Couscous
Bring water to a boil in a saucepan.
Stir in couscous, add chickpeas put the lid on the pot, remove pot from heat and let swell for about 5 minutes.
Mix in spices, olive oil and butter to loosen the couscous.
Garnish and serve
Roughly chop cashews and roast in a pan without fat.
Wash and coarsely chop the parsley.
Cut cauliflower into slices.
To serve, spread couscous on plates, top with cauliflower, drizzle sauce over and serve with toasted cashews and chopped parsley.