Prepare Teriyaki Sauce: In a small bowl, whisk together soy sauce, water, brown sugar, honey, rice vinegar, sesame oil, garlic, and ginger. In another small bowl, mix cornstarch with water until smooth. Add the cornstarch mixture to the sauce and stir until well combined.
Cook the Noodles: Cook noodles according to package instructions. Drain and set aside.
Cook Steak & Shrimp: Heat 1 tbsp vegetable oil in a large skillet or wok over medium-high heat. Add the steak and cook for 2–3 minutes per side until browned. Remove steak and set aside. Add shrimp to the same skillet and cook for 2–3 minutes until pink and opaque. Set shrimp aside.
Cook Vegetables: In the same skillet, add the remaining oil. Sauté broccoli, bell pepper, and snap peas for 4–5 minutes until tender-crisp.
Combine: Add noodles, steak, shrimp, and teriyaki sauce to the skillet with vegetables. Toss until everything is well coated and heated through, about 2–3 minutes.
Garnish & Serve: Transfer to plates and garnish with green onions and sesame seeds. Serve immediately.