Heat 1 tablespoon oil in large nonstick skillet over medium-high heat until shimmering. Add bok choy stems and cook until just tender, about 3 minutes. Add bok choy greens and cook until wilted, about 2 minutes. Add ginger, 2 teaspoons chili-garlic sauce, and 1/4 teaspoon salt and cook until fragrant, about 30 seconds. Transfer bok choy mixture to colander, tent with foil and let drain.
Whisk plum sauce, soy sauce, vinegar and remaining chili-garlic sauce in small bowl. Pat chicken dry with paper towels and season with salt and pepper. Heat 1 tablespoon oil in empty skillet over medium-high heat until just smoking. Cook half of the chicken until no longer pink about 3 minutes; transfer to plate and repeat with remaining oil and chicken.
Return first batch of chicken with juices to skillet. Stir in plum sauce mixture and scallions and cook until thickened about 1 minute. Transfer bok choy to platter and top with chicken. Serve with Asian noodles or white rice. ( I actually serve it this way because my family likes it this way...rice or noodles in bowl top with chicken mixture and then top with bok choy mixture). This is a very spicy dish!