Preparation

Make the yogurt-mint sauce

• In a small bowl, combine the lemon juice and grated garlic. Let sit 5 minutes to allow the garlic to mellow. Add the yogurt, 3/4 tsp. salt, and 1/4 tsp. pepper, and stir to combine. Transfer 1/2 cup of the garlic yogurt to a small bowl, and set aside. Stir the mint and dill into the remaining sauce. (The yogurt sauce can be made up to 1 day ahead. Store in an airtight container in the refrigerator.)

Roast the cauliflower, chickpeas, and tomatoes

• Position a rack in the center of the oven, and heat the oven to 450°F. Coat a large rimmed baking sheet with cooking spray.
• Put the chickpeas and tomatoes on the baking sheet, and toss with the olive oil, 11/2 tsp. of the cumin, 1/2 tsp. of the cinnamon, 1/2 tsp. salt, and 1/4 tsp. pepper. Nudge the tomatoes and chickpeas to the sides, and arrange the cauliflower steaks in a single layer on the baking sheet.
• Mix the remaining 1 tsp. cumin and 1/2 tsp. cinnamon into the reserved 1/2 cup garlic yogurt. Spread half of the yogurt over the cauliflower steaks, and season with 3/4 tsp. salt and 1/2 tsp. pepper. Roast the vegetables for 15 minutes. Carefully flip the cauliflower steaks over, top with the remaining yogurt, and gently stir the tomatoes and chickpeas. Continue roasting until the cauliflower is tender and lightly browned, 15 to 20 minutes longer.
• To serve, spread the yogurt sauce  on plates. Arrange the cauliflower steaks on top, and spoon the chickpeas and tomatoes over top. Sprinkle with crumbled feta, and garnish with chopped mint and dill. If you like, serve with naan or pita bread.