Add beef, soy sauce, rice vinegar, brown sugar, garlic, and ginger to a large bowl and mix to combine. Set aside at room temperature to marinate while you prepare the sauce and rice, about 20 minutes. 

When the other components are ready, heat a large skillet over medium heat and add the olive oil. 

When the oil is just barely warm (not hot), add the bulgogi (both the beef and marinade).

Cook for 5-7 minutes or until the liquid has evaporated and the beef is just beginning to crisp. 

When the beef is cooked to your desired doneness, remove it from the heat. 

Whisk together all of the ingredients in a small bowl. Set aside until ready to use. 

Heat a small skillet over medium heat. Add the olive oil. 

When the oil is hot, place the bok choy cut side down. Sear for 2-3 minutes or until the bok choy is crisp and browned. 

Flip the bok choy and cook it for an additional 2-3 minutes or until it is your desired doneness. 

Divide the rice, bulgogi, and boy choy between four bowls.

Top with the tahini-soy sauce and garnish with green onions and sesame seeds.