In a mixing bowl, whisk together soy sauce, sesame oil, brown sugar, rice vinegar, chili garlic sauce, cornstarch, 2 tsp grated ginger, 2 minced garlic cloves, and 1/4 tsp red pepper flakes to make the marinade.
Add the raw ground beef to the bowl and stir to fully coat with the marinade; set aside to marinate for 20 minutes.
Heat a large sauté pan or wok over medium-high heat and add 1 tbsp canola oil.
Add the trimmed, halved green beans and cook, stirring often, until they begin to blister and soften, about 3–4 minutes.
Add the remaining grated ginger (1 tbsp) and the 4 finely minced garlic cloves plus red pepper flakes; cook 30–60 seconds until fragrant. Remove the green beans from the pan and set aside.
Increase heat to medium-high if needed and add the marinated ground beef to the pan; cook, breaking up with a spatula, until browned and mostly cooked through.
Return the reserved green beans to the pan and stir to combine with the beef. Continue cooking until excess moisture has evaporated and the sauce thickens slightly, about 2–4 minutes.
Taste and adjust seasoning with more red pepper flakes or soy sauce if desired, then remove from heat and serve.
