Sprinkle the beef with salt & pepper. Add the beef, 1 tablespoon rice vinegar & 1 tablespoon soy sauce to a bowl and toss to coat. Let the beef marinate while you make the sauce.
In a small bowl, stir together the ingredients for the sauce: ginger, garlic, ¼ cup soy sauce, honey, 1 tablespoon rice vinegar, and hoisin.
In a large skillet (or wok) over medium high heat, add 1 tablespoon oil. Cook the beef for about 2 - 3 minutes on each side, until browned and barely cooked through. Set aside along with any juices from the pan.
Add another tablespoon of oil to the pan. Cook the vegetables over medium heat until tender, about 6 - 8 minutes. Sprinkle with salt & pepper to taste.
While the vegetables cook, add the sauce to a small skillet. Bring to a boil and then simmer 3 - 4 minutes, until thickened.
Add the beef back into the pan with the vegetables (don’t add any of the juices back into the pan). Pour the sauce into the pan and gently stir to mix. Sprinkle with red pepper flakes (optional for spice).
Optionally, serve with a side of rice and garnished with chopped green onions and sesame seeds.