Heat the sesame oil in a large pot over medium heat. Add the ground beef, minced ginger, and garlic. Cook until the beef is browned and broken into small pieces, about 5 minutes.
Stir in the diced onion, sliced carrots, and red bell pepper. Cook for 3 minutes until the vegetables begin to soften.
Pour in the beef broth and soy sauce. Bring the mixture to a simmer and cook for 8 minutes.
Add the chopped bok choy and simmer for 3 more minutes until it wilts but stays bright.
Remove the pot from heat and divide the stew into bowls. Top each serving with sliced green onions.