Pat beef dry with paper towels, season generously with salt and pepper. Place in a large mixing bowl and toss with cornstarch until well combined.
In a large skillet over medium-high heat add healthy drizzle of olive oil, cook green beans for 3 minutes. Add 2 tablespoons of water, and cover to steam, 3 more minutes. Transfer green beans to plate, and discard any excess water.
Return skillet to high heat and add another drizzle of olive oil. When almost smoking, add beef. Stir-fry beef until almost cooked through, 2-3 minutes. Reduce to medium heat and add garlic, ginger, soy sauce, vinegar, and sugar. Stir well to combine and coat the beef. Add back green beans, then top with green onions and sesame seeds.
Recipe by the minimalist table at https://www.daraboxer.com/theminimalisttable/sesame-ginger-beef/