Heat 2 tablespoons vegetable oil in a large skillet over medium-high heat until shimmering.
Add sliced chicken breast; cook 5-7 minutes until browned and cooked through, stirring often.
Toss in minced garlic and ginger; sauté 1 minute until fragrant.
Add bell pepper and onion slices; stir-fry 3-4 minutes till crisp-tender.
Mix gochujang, soy sauce, sesame oil, and honey in a bowl for the sauce.
Pour sauce over everything; stir to coat, cook 2-3 minutes till thickened.
Garnish with sesame seeds and green onions; serve hot over rice.