Rinse the quinoa, then place into a small pot. Cover with 2 cups water or broth and add ½ tsp salt. Bring the liquid to a boil, then reduce to a simmer, cover, and cook for 15 minutes, or until all the water is absorbed. Turn off the heat, and keep covered an additional 10 minutes.
Mix the shawarma spice blend until all ingredients are evenly distributed.
Rinse, drain, and dry the chickpeas. Be sure to dry thoroughly with a cotton kitchen towel or paper towels. Toss with 1 tbsp olive oil, then spread onto a baking sheet.
Toss the cauliflower with the remaining tablespoon of olive oil and just over half the spice blend. Set the remaining spice blend aside to use later. Spread the cauliflower onto a second baking sheet.
Place the baking sheets in the oven and roast, rotating once halfway through, about 30 minutes total. The chickpeas are done when they’re golden browned and crisp. The cauliflower is done when you can easily pierce the stems with the tip of a sharp knife.
While the cauliflower and chickpeas are roasting, make the tomato cucumber salad. Place the tomatoes, cucumbers, red onion, mint and parsley in a small bowl, season with ½ tsp salt and ½ tsp pepper and toss.
Remove the chick peas from the oven and toss with the remaining spice blend and lemon zest.
Remove the cauliflower from the oven and sprinkle with the lemon juice.
Assemble the shawarma bowls. Divide the cooked quinoa between 4 bowls. Top with one-quarter of the chickpeas, one-quarter of the cauliflower, and one-quarter of the tomato cucumber salad. Drizzle with tahini dressing to taste and serve immediately.