Slice chicken into thin strips about 1/4-inch thick, cutting against the grain for tenderness. Cut zucchini into half-moon slices about 1/4-inch thick, and slice bell pepper into strips. Mince garlic finely. In a small bowl, whisk together soy sauce, oyster sauce, honey, and sesame oil until well combined. Set aside.

Heat 1 tablespoon of vegetable oil in a large skillet or wok over medium-high heat until it shimmers but doesn't smoke. Add sliced chicken in a single layer, season with salt and pepper, and let cook undisturbed for 2-3 minutes to develop a golden crust. If pan is smaller than 12 inches, work in batches. Flip and cook for another 2-3 minutes until internal temperature reaches 165°F and chicken is no longer pink inside. Transfer to a clean plate.

Add remaining tablespoon of oil to the same pan. Toss in zucchini and bell pepper, stirring frequently for 3-4 minutes until just tender but still crisp. Vegetables should be bright in color and crisp-tender. Add minced garlic and stir constantly for 30 seconds until fragrant but not browned, as burned garlic turns bitter.

Return cooked chicken to the pan along with any accumulated juices. Pour in the prepared sauce and toss vigorously to coat all ingredients evenly. Cook for 1-2 minutes, stirring constantly, until sauce thickens enough to cling to chicken and vegetables and everything is heated through and glossy.

Remove from heat and transfer to a serving dish. Garnish generously with sesame seeds and sliced green onions. Serve immediately while hot over rice, noodles, or as-is.