In a large bowl, toss together the coleslaw mix, radishes, cilantro, and scallions. Set aside.
In a small bowl, whisk together 1 tablespoon of lime juice, lime zest, and olive oil. Pour over the coleslaw mixture and toss to coat.
In the small bowl, stir together the yogurt and the remaining 1 tablespoon of lime juice. Season to taste with salt and ground black pepper.
Stir the yogurt mixture into the slaw mixture and toss to coat. Adjust the seasoning to taste, and serve cool or at room temperature.