Wash and drain all vegetables. Cut broccoli into bite-size florets (about 2 cups). Cut cauliflower into similar bite-size florets (1 cup). Peel and slice carrot thinly on a bias (1 cup). Core and thinly slice red bell pepper (1 cup). Trim snap peas and halve any very large pods. Thinly slice 1/2 cup yellow onion. Mince 3 cloves garlic and 1 tablespoon fresh ginger.

Measure out sauce ingredients: combine 3 tablespoons soy sauce, 1 tablespoon oyster (or mushroom) sauce, 1 teaspoon sesame oil, 1 teaspoon rice vinegar, 1 teaspoon honey, 1/4 teaspoon red pepper flakes, 1/4 teaspoon salt and 1/8 teaspoon black pepper in a small bowl. In a separate small cup, dissolve 1 teaspoon cornstarch into 3 tablespoons water to make a slurry; set both aside.

Cooking

Blanch firmer vegetables (optional for even cooking)

Bring a medium pot of water to a rolling boil and add a generous pinch of salt. Add broccoli and cauliflower florets and blanch 1 minute. Using a slotted spoon transfer to a bowl of ice water to stop cooking; drain and set aside. (This step keeps colors bright and ensures even tenderness; you can skip and cook everything in the pan if you prefer.)

Stir-fry aromatics

Heat a large wok or wide skillet over medium-high heat until hot. Add 2 tablespoons vegetable oil and swirl to coat. Add the sliced onion and stir-fry 1–2 minutes until it starts to soften. Add the minced garlic and ginger and stir-fry 20–30 seconds until fragrant, taking care not to burn them.

Cook vegetables

Add the carrot slices and bell pepper to the pan and stir-fry 1–2 minutes. Add the snap peas and the blanched broccoli and cauliflower (or raw florets if you skipped blanching). Stir-fry, tossing constantly, 2–3 minutes more until vegetables are crisp-tender. If the pan becomes dry, add a splash (1–2 tablespoons) of water to create steam and prevent burning.

Finish with sauce

Give the prepared sauce one quick stir then pour it over the vegetables. Stir to coat. Immediately pour in the cornstarch slurry while stirring; cook 30–60 seconds until sauce thickens and becomes glossy and evenly coats the vegetables. Taste and adjust seasoning with additional salt or soy sauce if needed.

Turn off heat and drizzle 1 teaspoon sesame oil over the vegetables; toss to combine.

Serve

Transfer the mixed vegetables to a serving bowl or plates. Sprinkle with toasted sesame seeds and sliced green onions. Serve hot with lime wedges on the side if desired. This pairs well with steamed rice or noodles.

Leftovers: cool to room temperature, store in an airtight container in the refrigerator for up to 3 days. Reheat gently in a skillet over medium heat, adding a splash of water if sauce has tightened.