In a small bowl, combine the cornstarch and cold water, whisking until smooth. Set this slurry aside for later use.
Heat the vegetable oil in a large skillet or wok over medium-high heat until shimmering.
Carefully add the sliced chicken to the hot skillet, seasoning it with salt and pepper. Cook for about 5-7 minutes, stirring occasionally, until the chicken is browned and no longer pink in the center. Once cooked, transfer the chicken to a plate and set aside.
In the same skillet, add the minced garlic and grated ginger. Sauté for about 30 seconds, stirring frequently, until the mixture is aromatic but not burnt.
Add the strips of mixed bell peppers, broccoli florets, and julienned carrots to the skillet. Stir-fry the vegetables for about 4-5 minutes, or until they reach a tender-crisp texture, maintaining their vibrant colors.
Return the cooked chicken to the skillet, incorporating it with the vegetables. Drizzle the soy sauce and sesame oil over the entire mixture, stirring well to ensure even distribution of the flavors.
Pour the prepared cornstarch slurry into the skillet and stir continuously for 1-2 minutes, allowing the sauce to thicken and coat all the ingredients nicely.
Remove the skillet from heat and sprinkle sesame seeds generously over the dish for added texture and flavor.
Notes
Serve artistically arranged atop rice or noodles, and garnish with sesame seeds and cilantro for added appeal.