Roasting is a great way to get a rich taste without a lot of fuss. The intense heat concentrates flavors and helps foods brown, crisp, and caramelize.
Preheat oven to 475 degrees. In an 11-by-15-by-2 3/4-inch roasting pan, combine carrots, cauliflower, 1 teaspoon coriander, 1/2 teaspoon cumin, 3/4 teaspoon salt, and 1/2 teaspoon pepper; arrange around sides of pan.
Place chicken legs along center of pan, and sprinkle with remaining 1/2 teaspoon coriander and 1/4 teaspoon cumin; season generously with salt and pepper.
Roast, stirring vegetables once, until chicken is well browned and crispy and an instant-read thermometer inserted in a thigh (without touching bone) registers 180 degrees, 40 to 45 minutes. Transfer chicken to a platter, and let rest for 5 minutes.
Meanwhile, add lemon juice to pan; with a wooden spoon, stir and scrape up drippings, mixing with vegetables. Serve.