Preheat the oven to 425°F (220°C).
In a mixing bowl, combine ground coriander, cumin, paprika, minced garlic, olive oil, lemon zest, salt, and pepper. Mix to create a marinade.
Add the chicken thighs to the marinade, ensuring they are well-coated. Let them marinate for at least 10 minutes.
On a baking sheet, arrange the cauliflower florets. Drizzle with olive oil, season with salt and pepper, and toss to coat.
Place the marinated chicken thighs on the same baking sheet, skin side up.
Roast in the preheated oven for 30-35 minutes, until the chicken is cooked through and the skin is golden and crispy, and the cauliflower is tender and slightly caramelized.
While the chicken and cauliflower are roasting, prepare the herbed yogurt: In a bowl, mix together the Greek yogurt, chopped cilantro, chopped mint, lemon juice, and salt. Stir until well combined.
Once cooked, remove the chicken and cauliflower from the oven. Let rest for a few minutes before serving.
Serve the coriander chicken thighs with roasted cauliflower, drizzled with the herbed yogurt.