1. Slice pork tenderloin lengthwise, cutting to, but not through other side. Open halves, laying pork flat. Place plastic wrap over pork; pound to ¼-inch thickness. Cut pork crosswise into 4 steaks; sprinkle with salt.

2. Heat a large nonstick skillet over medium-high heat. Coat pan with cooking spray. Add pork; cook 3 to 4 minutes on each side or until done. Transfer pork to a plate. Reduce heat to low.

3. While pork is cooking, cut bok choy in half lengthwise, leaving core intact. Steam bok choy, covered, 4 minutes or until tender; drain well.

4. Combine vinegar and remaining ingredients in a small bowl, stirring with a whisk. Stir vinegar into pan drippings; cook 1 minute. Return pork to skillet; remove from heat. Let stand 2 to 3 minutes or until thoroughly heated, turning often.

5. While pork is reheating, heat a large nonstick skillet over medium-high heat. Coat pan with cooking spray. Drizzle cut sides of bok choy with oil; sprinkle with salt and pepper. Place bok choy, cut sides down, in pan; cook 6 minutes or until lightly browned. Turn bok choy over; cook an additional 1 to 2 minutes or until lightly browned. Sprinkle with sesame seeds.