Rinse the bok choy well and pat dry. Trim the base, separate the stems from the leafy greens, and chop stems into 1-inch pieces and leaves into larger bite-sized pieces.

Clean mushrooms with a damp towel and slice them. Mince garlic and ginger.

Heat 1–2 tablespoons vegetable oil in a large skillet or wok over medium-high heat until shimmering.

Add the bok choy stems and stir-fry for 2–3 minutes until they start to soften and pick up color.

Push stems to the side and add mushrooms. Let mushrooms cook undisturbed for 1–2 minutes to brown, then stir and cook another 2 minutes until they release most of their liquid.

Stir the stems and mushrooms together. Add minced garlic and ginger; cook 30–45 seconds until fragrant (don’t let garlic burn).

Pour in soy sauce and optional oyster sauce; toss to coat and let pan reduce slightly, about 30–60 seconds.

Add the bok choy leaves, toss until just wilted (30–60 seconds). Remove from heat and finish with sesame oil and a few grinds of black pepper.

Taste and adjust seasoning: add a splash more soy or a pinch of salt if needed.

Serve immediately over steamed rice, with noodles, or as a side to grilled fish or tofu.