Heat oven to 450° F. Heat 2 tablespoons of the oil in a large ovenproof skillet over medium-high heat. Season the chicken with the coriander and ¾ teaspoon each salt and pepper. Cook, skin-side down, until the skin is golden brown and crisp, 6 to 8 minutes. Flip the chicken and transfer the pan to oven. Cook until an instant-read thermometer inserted in the center of the thickest breast (avoiding bone) registers 165° F, 22 to 25 minutes.
Meanwhile, cook the lentils according to the package directions; drain and cool slightly. Toss in a large bowl with the radicchio, clementine slices, cilantro, 1 tablespoon of the olive oil, and ¼ teaspoon each salt and pepper.
Whisk the yogurt, tahini, clementine juice, the remaining tablespoon of olive oil, and ¼ teaspoon each salt and pepper in a small bowl.
Serve the chicken and salad drizzled with the dressing and topped with additional cilantro.