Preheat the oven to 425°F (220°C) and line a baking sheet with parchment paper.
Remove the leaves and stem from the cauliflower and cut it into bite-sized florets.
In a large mixing bowl, combine olive oil, cumin, coriander, smoked paprika, turmeric, salt, and black pepper. Add the cauliflower florets and toss until evenly coated.
Spread the seasoned cauliflower evenly on the prepared baking sheet and roast for 20-25 minutes or until tender and golden brown, stirring halfway through.
While the cauliflower roasts, prepare the tahini sauce by whisking together tahini, lemon juice, minced garlic, and a pinch of salt. Gradually add water until desired consistency is reached.
To assemble the bowls, divide quinoa or rice among four serving bowls, then top with roasted cauliflower, mixed greens, cherry tomatoes, sliced red onion, and diced cucumber.
Drizzle the bowls with tahini sauce and garnish with fresh parsley if desired.
Serve immediately and enjoy your delicious Cauliflower Shawarma Bowls!