Preheat the oven to 425°F. Line a baking sheet with parchment paper.
Prep the cauliflower: To get two slabs and a bunch of loose florets cut the cauliflower head in half. Cut each half into another half in the same direction. The result from each half should be a thick slab of cauliflower from the inside part of the cauliflower and loose florets from the outside of the head of the cauliflower.
Bake the cauliflower: Mix the harissa and olive oil. Add the cauliflower to the baking sheet. Use a brush or a spoon or your hands to coat all of the cauliflower with the harissa mixture. Season with salt and pepper. Bake for 20 minutes, flip the cauliflower, and bake for another 10-15 minutes or until the cauliflower is done to your liking.
For the Hummus
Add hummus ingredients, except the ice to a food processor. Blend well. Add an ice cube and blend for another 3-5 minutes until smooth. Add another ice cube if necessary.
For the Tahini Yogurt
Whisk together the tahini, yogurt, and lemon juice. Season with salt and pepper., The sauce thickens up a lot. Add water, a little at a time, as needed The sauce will thicken drastically before finally thinning out.
For the Crispy Chickpeas
Dry chickpeas well with a paper towel or kitchen towel. Heat a skillet with a tablespoon of oil. Add chickpeas and cook, stirring occasionally for 6-8 minutes. Add a pinch of cumin and cayenne, stir, and remove from heat. Season with salt and pepper.
To Serve
For each plate, spread a quarter of the hummus on the bottom of the plate. Add either a cauliflower slab or half of the florets. Drizzle the tahini yogurt sauce on top and sprinkle with 1/4 of the crispy chickpeas. I served mine with a handful of arugula mixed with oil and lemon juice.