Season the beef with salt and pepper. In a dutch oven, heat the olive oil over medium-high heat. Add the beef and cook, turning, until browned, about 8 minutes. Add 2 1/2 cups water, the chicken broth and garlic. Lower the heat, cover and simmer for 20 minutes. Nestle the chicken into the liquid, add the carrots and cabbage, cover and simmer for 30 minutes. Add the leeks and simmer until the chicken is cooked through, about 15 minutes.
Transfer the vegetables to a platter and tent with foil. Transfer the beef and chicken to a cutting board and slice; arrange on the platter. Add the bok choy to the cooking liquid in the pot, cover and cook until tender, 3 to 4 minutes; transfer to the platter. Serve the meat and vegetables in shallow bowls moistened with the cooking liquid.