Preheat the oven to 400 degrees Fahrenheit. In a large bowl, toss the cauliflower and red onion with grapeseed oil and salt and pepper. Place on a large baking sheet and roast for 20 minutes, or until the cauliflower is browned on the edges. Remove from the oven and allow to cool.
In a bowl, toss the chickpeas with grapeseed oil, smoked paprika, coriander, garlic powder, cayenne, salt and pepper. Place on a baking sheet and roast along with the cauliflower/red onion mix for about 15 minutes, or until they sizzle and become slightly crispy.
While the cauliflower and chickpeas are roasting, prepare the Lemon Tahini Dressing. In a blender or food processor, add the tahini, water, lemon juice, garlic, cumin, cayenne and salt. Blend until smooth and refrigerate until serving. The dressing will keep for 3-4 days.
Assemble the salad by tossing the roasted cauliflower, red onion, and chickpeas in a bowl with the dressing. Add chopped parsley and cilantro. May be served warm or cold.
