In a medium bowl, combine thinly sliced beef flank steak with Shaoxing wine, salt, black pepper, and half of the cornstarch. Mix well and marinate for 15 minutes.

While the beef marinates, whisk together chicken broth, soy sauce, remaining Shaoxing wine, rice vinegar, sesame oil, sugar, garlic, and the rest of the cornstarch until smooth.

Heat a large skillet over medium-high heat with peanut oil until shimmering. Add the marinated beef in a single layer and cook for about 1 minute until golden brown, then flip and cook for an additional minute.

Reduce the skillet heat to medium-low, pour the prepared sauce over the beef, and cook until the sauce thickens, about 2-3 minutes.

Remove from heat, transfer the sesame beef to a serving dish, and garnish with toasted sesame seeds. Serve warm over steamed rice.