Finely shred peel from lemon; set peel aside. Juice lemon and set juice aside. Season chicken lightly with salt and pepper.
In a Dutch oven heat olive oil over medium-high heat; add chicken. Cook for 2 to 3 minutes or until chicken is browned, turning occasionally.
Add carrots, gravy, and the water to Dutch oven. Stir in mustard. Bring to boiling. Place bok choy on top. Reduce heat. Cover and simmer for 10 minutes or until chicken is done and vegetables are just tender. Add lemon juice to taste.
Ladle stew into bowls. Top with lemon peel and lemon thyme.