How to Make It
Place coleslaw mix in a colander; toss with granulated sugar and 1 teaspoon salt. Let stand 20 minutes. Meanwhile, place potatoes in a saucepan; cover with water. Bring to a boil; cook until tender, about 15 minutes. Drain. Rinse and drain slaw. Combine yogurt, chives, 2 tablespoons mayo, Dijon, and 1/2 teaspoon salt in a bowl. Stir in potatoes.
Combine garlic powder, brown sugar, paprika, cumin, cayenne, and remaining 1/4 teaspoon salt. Brush chicken with 1 tablespoon oil; sprinkle with spice rub. Heat a grill pan over medium-high. Add chicken; grill until done, about 6 minutes per side.
Stir together vinegar, remaining 1 tablespoon mayo, and remaining 1 tablespoon oil in a bowl. Stir in slaw. Serve with chicken and potato salad.