Make the sriracha mayo by mixing up all the ingredients for the sauce.
Rinse rice in a mesh strainer under cold water for 2 minutes, then combine with 450g of water and bring to a boil. Once boiling, reduce heat to low, cover, and let cook for 15 minutes. Remove from heat, keep covered, and let sit another 10 minutes to cook rice.
Make the beef marinade by combining sesame oil, minced garlic, brown sugar, soy sauce and Gojujang. Cook the lean beef and add in the marinade once it's 50% cooked through. Toss in chopped green onions and let it simmer for ~5 minutes or until the beef is fully cooked.
Assemble 5 bowls with rice, beef, and top with the homemade sriracha mayo and sesame seeds.