Halve and rinse 1 pound baby bok choy. Microwave, covered, until crisp-tender, about 4 minutes. Whisk 2 tablespoons peanut oil, 1 tablespoon each honey and rice vinegar and 2 teaspoons each Sriracha and toasted sesame oil. Drain the bok choy; toss with the dressing. Grill, turning, until charred, about 4 minutes. Drizzle with any remaining dressing and sprinkle with toasted sesame seeds.