Whisk together soy sauce, sriracha, brown sugar, and toasted sesame oil in a small bowl to create the stir-fry sauce.
Heat 1 tablespoon of vegetable oil in a large skillet or wok over medium-high heat.
Add broccoli and red bell pepper to the skillet and stir-fry for 3-4 minutes until crisp-tender, then remove vegetables and set aside.
Add the remaining tablespoon of oil to the same skillet and brown the ground beef, breaking it into small crumbles, until fully cooked.
Incorporate the minced garlic, grated ginger, and red pepper flakes into the beef and cook for 60 seconds until aromatic.
Return the cooked vegetables to the skillet and pour the prepared sauce over the mixture.
Toss all ingredients together for 2 minutes over heat until the sauce thickens slightly and evenly coats the beef and vegetables.
Portion the stir-fry over bowls of steamed jasmine rice and garnish with sliced green onions.