Step 1: Prepare your sauce by whisking together soy sauce, oyster sauce, rice vinegar, sesame oil, sugar, and 2 tablespoons of water in a small bowl until the sugar dissolves.

Step 2: Trim the stem ends from 1.5 pounds of green beans and pat them completely dry with paper towels to ensure proper charring.

Step 3: Heat a wok or large skillet over high heat for 2 minutes until it is smoking hot and a drop of water sizzles on contact.

Step 4: Add 1.5 tablespoons of vegetable oil to the hot wok, swirl to coat, then add half the beans in a single layer and sear undisturbed for 2 minutes until brown and blistered.

Step 5: Stir the seared beans and cook for an additional 2 to 3 minutes until speckled with brown, then transfer them to a plate and repeat with the remaining oil and beans.

Step 6: Return all beans to the wok, reduce heat to medium-high, add minced garlic and ginger, and stir constantly for 30 seconds until fragrant.

Step 7: Pour in the prepared sauce, toss the beans continuously for 1 to 2 minutes until the sauce reduces slightly and coats each bean in a glossy finish.

Step 8: Remove from heat, taste and adjust seasoning if needed, then sprinkle with sesame seeds, sliced green onion, and optional red pepper flakes before serving immediately.