Wash and prepare all vegetables as listed: thinly slice the onion and red pepper, peel and slice carrots on the bias, cut broccoli into bite-sized florets, halve and slice the zucchini, trim snap peas, and measure out the spinach. Mince the garlic and grate the ginger. In a small bowl whisk together soy sauce, oyster (or mushroom) sauce, rice vinegar, honey (or maple), and sesame oil. In a separate small cup dissolve the cornstarch in 2 tablespoons cold water to make a slurry.

Heat pan and aromatics

Place a large skillet or wok over medium-high heat until hot. Add the olive oil and butter. When butter has melted and begins to foam, add the minced garlic and grated ginger and sauté for 20–30 seconds until fragrant but not browned.

Cook firmer vegetables

Add the sliced onion and carrots to the pan. Stir-fry for 2 minutes, then add the broccoli florets and red bell pepper. Continue stir-frying, tossing frequently, for 3–4 minutes until the carrots and broccoli begin to become tender-crisp.

Add quick-cooking vegetables

Add the zucchini and snap peas to the pan and stir-fry for another 2 minutes until zucchini is slightly softened and peas are bright green. Season lightly with 1/4 teaspoon of the kosher salt and a pinch of black pepper while cooking.

Add sauce and thicken

Give the prepared sauce a quick stir and pour it over the vegetables. Toss to combine and coat. Pour in the cornstarch slurry and stir constantly as the sauce comes to a gentle simmer; cook 1–2 minutes until the sauce thickens and becomes glossy and coats the vegetables.

Finish with greens and adjust seasoning

Add the baby spinach and toss until wilted, about 1 minute. Taste and adjust seasoning with remaining 1/4 teaspoon kosher salt, additional soy sauce, or a splash of rice vinegar if desired. Add the sesame oil and toss once more.

Garnish and serve

Remove from heat. Transfer the stir-fry to a serving bowl or divide over cooked rice. Garnish with sliced green onions and toasted sesame seeds. Sprinkle optional red pepper flakes if you like heat.

To Serve (optional)

Portion about 1 cup of cooked rice per serving and top with 1 to 1 1/4 cups of the vegetable stir-fry. Serve immediately while hot.