Preheat the oven to 425°F. Line a sheet pan with parchment paper.
Prepare the chickpeas and cauliflower: In a large bowl, stir together the oregano, basil, parsley, garlic powder, salt, and black pepper. Add the cauliflower, chickpeas, and oil and toss until fully coated. Transfer the mixture to the prepared sheet pan and spread out in a single layer. Place the lemon halves cut side down in the center.
Bake until the chickpeas are crispy and the cauliflower is fork-tender, 18 to 20 minutes.
Meanwhile, make the lemon-dill sauce: In a small bowl, whisk together the yogurt, parsley, dill, oil, garlic powder, and salt until combined.
When the cauliflower and chickpeas are done and the roasted lemons are cool, squeeze the juice into the dill sauce. Stir to combine.
Assemble the bowls: Divide the rice among four bowls and top with the cauliflower and chickpeas. Drizzle with sauce and garnish with herbs.
