Prep the veggies: Wash and dry well.
Cut into similar-sized pieces so they cook evenly. Keep dense veggies (carrots, broccoli stems) on the smaller side; tender veggies (zucchini, mushrooms) a bit larger.
Make the sauce: In a small bowl, whisk soy sauce, oyster sauce (if using), sesame oil, rice vinegar, honey, garlic, ginger, and chili flakes. In another small cup, stir cornstarch with water until smooth.
Mix the slurry into the sauce.
Toss with oil: In a large bowl, toss the veggies with the neutral oil. Season lightly with salt and pepper. Don’t add the sauce yet.
Preheat the air fryer: Set to 375°F (190°C) for 3 minutes.
A warmed basket helps with browning.
Air fry, round one: Add veggies in a loose, even layer—avoid packing tightly. Cook for 6 to 8 minutes, shaking the basket halfway through. They should start to soften and brown at the edges.
Sauce and finish: Transfer hot veggies back to the mixing bowl.
Pour over the sauce and toss until coated. Return to the air fryer and cook 2 to 3 more minutes at 375°F, shaking once. The sauce should thicken and cling.
Taste and adjust: Add another splash of soy for salt, a squeeze of lime for brightness, or a pinch of sugar if it tastes too sharp.
Garnish and serve: Sprinkle with sesame seeds and green onions.
Serve immediately with rice, noodles, or your protein of choice.