Step 1

In a large bowl, whisk yogurt, tandoori seasoning and, if desired, pepper flakes until blended. Add chicken and turn to coat. Cover and refrigerate 6-8 hours, turning occasionally. Preheat oven to 450°. Drain chicken, discarding marinade in bowl. Place chicken in a greased 15x10x1-in. baking pan. Add sweet potatoes; drizzle with oil. Bake 15 minutes. Add tomatoes and lemon slices. Bake until a thermometer inserted into chicken reads 170°-175°, 10-15 minutes longer.

Step 2

Broil 4-5 in. from the heat until browned, 4-5 minutes. If desired, serve with cilantro and naan.