Preheat oven to 425 degrees F. Coat a large rimmed baking sheet with cooking spray.
Whisk oil, curry powder, and ½ tsp. salt in a large bowl. Add cauliflower and chickpeas; toss to coat. Spread evenly on the prepared baking sheet. Roast, stirring once, until tender and browned in spots, about 20 minutes.
Meanwhile, combine 1 ¼ cups water, quinoa, and the remaining ¼ teaspoon salt in a medium saucepan. Bring to a boil over medium-high heat. Reduce heat to medium-low, cover, and simmer until the quinoa is tender, 12 to 15 minutes. Remove from the heat and fluff the quinoa with a fork. Stir in spinach, cover, and let stand for 5 minutes.
Meanwhile, whisk tahini, lime zest, lime juice, garlic, pepper, and the remaining 2 Tbsp. water in a small bowl.
Divide the quinoa mixture among 4 dinner bowls. Top with the cauliflower-chickpea mixture and a drizzle of the tahini dressing.
