How to Make It
Heat a grill pan over high. Coat pan with cooking spray. Place bok choy halves, cut side down, on pan. Cook 2 minutes per side, until both sides are marked and lightly charred. Remove from pan.
Stir together buttermilk, blue cheese, vinegar, sugar, and pepper in a bowl. Place bok choy halves, cut side up, on a serving platter. Top evenly with buttermilk dressing, and sprinkle evenly with tomatoes and fried onions.