Make the teriyaki sauce. In a bowl, whisk 1/4 cup soy sauce, 2 tablespoons mirin or 1 tablespoon honey, 1–2 teaspoons brown sugar (optional), 1 tablespoon rice vinegar, 1/2 cup water, and 1 tablespoon cornstarch until smooth. Set aside.

Prep the vegetables. Cut broccoli into bite-size florets, slice peppers and carrots thin, trim peas, slice mushrooms, and cut onion into wedges. Aim for uniform sizes so everything cooks evenly.

Heat the pan. Set a large skillet or wok over medium-high heat. Add 1–2 tablespoons neutral oil and let it shimmer.

Sauté aromatics. Add 2–3 minced garlic cloves and 1 tablespoon grated ginger. Stir for 20–30 seconds until fragrant. Don’t let them brown.

Cook the hearty veg first. Add carrots and broccoli. Stir-fry 2–3 minutes until they start to brighten and soften at the edges.

Add the rest. Toss in peppers, onions, and mushrooms. Stir-fry 2–3 more minutes. Add peas last so they stay crisp, cooking 1 minute.

Glaze with sauce. Give the sauce a quick stir (the cornstarch settles), then pour it around the pan. Stir constantly. In 1–2 minutes, it will thicken and coat the vegetables.

Finish and serve. Turn off the heat. Stir in 1 teaspoon sesame oil for a nutty finish. Sprinkle sesame seeds and sliced scallions. Serve over rice or noodles.