Step 1: Begin by gathering and washing all your vegetables. Chop the onion, bell pepper, carrots, and mushrooms into bite-sized pieces. Separate the broccoli into small florets and trim the snap peas. Mince your garlic and grate your fresh ginger.
Step 2: In a small bowl, whisk together the sauce ingredients: low-sodium soy sauce, oyster sauce (or vegetarian oyster sauce), rice vinegar, brown sugar, cornstarch, and water or vegetable broth until smooth. Set aside.
Step 3: Heat 1 tablespoon of sesame oil and 1 tablespoon of olive oil in your wok or large skillet over high heat until shimmering.
Step 4: Add the sliced yellow onion and stir-fry for 1-2 minutes until slightly softened and fragrant.
Step 5: Add the minced garlic and grated ginger to the wok. Stir-fry for another 30 seconds until aromatic, being careful not to burn the garlic.
Step 6: Add the harder vegetables first: broccoli florets and sliced carrots. Stir-fry for 3-4 minutes, tossing constantly, until they start to become tender-crisp.
Step 7: Next, add the red bell pepper, snap peas, sliced mushrooms, and baby corn (if using). Continue to stir-fry for another 2-3 minutes until all the vegetables are bright and tender-crisp. You want them cooked through but still retaining a slight crunch.
Step 8: Give your prepared sauce mixture a quick whisk again (cornstarch can settle) and pour it over the vegetables in the wok. Stir continuously as the sauce thickens, coating all the vegetables evenly. This should take about 1 minute.
Step 9: Remove the vegetable stir fry from the heat immediately. Garnish with sesame seeds and chopped green onions. Serve hot over cooked rice, noodles, or quinoa.