Directions

1. Whisk together yogurt, lemon juice, garlic, mustard, paprika, coriander, 2 tablespoons oil, 2 teaspoons salt, and 1 teaspoon pepper in a large bowl until smooth. Add chicken thighs; toss to coat, rubbing yogurt mixture evenly over chicken. Cover and refrigerate for at least 30 minutes or up to 4 hours.
2. Preheat oven to 425°F with racks in the upper and lower third positions. Toss potatoes and Broccolini with remaining 3 tablespoons olive oil, remaining 1 1/2 teaspoons salt, and remaining 1/2 teaspoon pepper in a large bowl until evenly coated. Arrange potatoes, cut sides down, in a single layer on a large rimmed baking sheet; set Broccolini in bowl aside. Remove chicken thighs from marinade; place chicken, skin side up, on a second large rimmed baking sheet; discard marinade. Arrange lemon halves, cut sides down, around chicken.
3. Place baking sheet with chicken on upper rack and baking sheet with potatoes on lower rack of oven; roast for 25 minutes. Remove potatoes from oven, and flip using a thin metal spatula; arrange Broccolini on baking sheet with potatoes. Return to oven; continue roasting until potatoes and Broccolini are tender and a thermometer inserted into thickest portion of chicken registers 165°F, 12 to 15 minutes.
4. Skim off fat from chicken pan juices and discard. Drizzle pan juices over chicken and vegetables. Serve hot.