Remove stalks from cauliflower head. Make sure it can sit flat. Heat a large pan of water that is big enough to cook the whole cauliflower submerged. When water is boiling, carefully add the cauliflower head. Cook for 6-8mins until you can insert a knife into the centre. Do not overcook it.
Mix together 4 Tbsp olive oil, 2 Tbsp za'atar, juice of 1/2 lemon and 3/4 tsp turmeric.
When cauliflower is cooked, remove it from the water and leave to stand for 5 mins to cool down and drain. Pat dry to remove any extra water.
Place cauliflower on an oven tray. Brush all over with the oil mixture you have just prepared. Place in the oven for 15 minutes.
Lay tomatoes on an oven tray. Drizzle with olive oil.
Make the tahini dressing by mixing all the ingredients together. Adjust seasoning to your own preference. Set aside.
After the cauliflower has been roasting for 15mins, add the tomato tray in the oven and cook together for 10-15mins. Check to make sure the cauliflower head is not getting too brown (cover it with foil if it does).
Cook couscous in boiling water according to packet instructions (it should take 10 mins). When done, drain well and mix with drained chickpeas, 1 tsp za'atar, 1 Tbsp chopped coriander, 1 Tbsp chopped parsley and 1 Tbsp chopped mint. Season with salt and lemon juice.
By now the tomatoes and cauliflower should be cooked. Remove both trays from the oven. Carefully pour the tomatoes juices into the couscous mixture.
Place the roasted cauliflower head on a serving dish. Scatter couscous mixture and tomatoes around it. Drizzle some tahini dressing all over. Top with pomegranate seeds, flaked almonds, chopped coriander leaves and chopped parsley leaves.
Serve straight away with the rest of the tahini dressing on the side.