Place the chopped cauliflower, red pepper, crushed garlic and sliced garlic bulb on a baking tray drizzled with the olive oil and some salt and pepper. Place in the oven at 180°C for 20-30 minutes until the cauliflower is charred around the edges.
While the cauliflower and peppers are cooking heat the vegetable oil over a medium heat and fry the onion gently for 10 minutes with some salt and pepper. Add the chick peas then fill the tin halfway up with water and add that to the pan too. Stir in the tomato puree and harissa paste and allow to cook until most of the water has evaporated, about 10 minutes. Add a squeeze of lime juice at the end of cooking.
When the cauliflower and chick peas are cooked assemble your salad by placing the cauliflower and peppers on the bottom of a serving dish. Add the spinach then dollop spoonfuls of the chick peas and yoghurt over the top. Squeeze the roasted garlic out of the skins and sprinkle over the top with the walnuts. Serve.