Wash, dry, and cut all vegetables as listed. Prepare the sauce by whisking together soy sauce, rice vinegar, sesame oil, optional sweetener, and cornstarch slurry in a small bowl. Have aromatics ready.
Place a large skillet or wok over high heat. Once hot, add the neutral oil and swirl to coat.
Add garlic and ginger, stir constantly for 15-20 seconds until fragrant, being careful not to burn them.
Add broccoli and carrots. Stir-fry for 2 minutes, tossing frequently. They will start to brighten and slightly char.
Toss in bell pepper, snap peas, and mushrooms. Continue stir-frying for another 2-3 minutes until all vegetables are tender-crisp and vibrant.
Give the sauce a quick stir and pour over the vegetables. Toss everything together and cook for 1 minute until the sauce thickens and coats the ingredients evenly.
Divide the cooked rice or quinoa among bowls, top with the vegetable stir-fry, and garnish with sesame seeds and green onions.