Step 1: In a small bowl, whisk together soy sauce, oyster sauce (if using), rice vinegar, and sugar. Set aside.
Step 2: Heat sesame oil and vegetable oil in a wok or skillet over medium-high heat. Add garlic and ginger. Stir-fry for 30 seconds until fragrant.
Step 3: Add chopped bok choy and sliced scallions. Stir-fry for 3–4 minutes, until wilted but still crisp-tender.
Step 4: Pour in the sauce. Toss everything together and stir-fry for another 1–2 minutes until evenly coated and heated through.
Step 5: Remove from heat and garnish with sesame seeds and crushed red pepper flakes. Serve hot on its own or over rice.
Notes
Swap bok choy for napa cabbage or spinach for variety. Add tofu or shrimp for a heartier dish. For extra sauce, double the soy mixture and drizzle over rice or noodles.