Partially freeze the steak for 1 hour before slicing for easier thin cuts.
In a large skillet, heat 1 tbsp vegetable oil over medium-high heat.
Add the steak and cook for 5-6 minutes until lightly browned; remove and set aside.
Add remaining 1 tbsp vegetable oil to skillet.
Add chopped bell peppers and onion; cook 3-4 minutes until tender.
Return the cooked steak to the skillet.
In a medium bowl, whisk together garlic, black pepper, ginger, brown sugar, soy sauce, beef broth, rice vinegar, sesame oil, and cornstarch until well combined.
Pour the sauce mixture into the skillet and stir to combine.
Bring to a simmer and cook for 4-5 minutes until the sauce thickens.
Serve hot over rice and garnish with sesame seeds. Enjoy!