Whisk together honey, hoisin sauce, ginger root, five-spice powder, 2 tablespoons chili oil, sesame oil, and garlic in a medium bowl. Pat steak dry with paper towels; thinly slice steak across the grain into bite-size strips. Add steak to honey mixture; toss to coat. Marinate at room temperature 10 minutes.

Cook udon noodles according to packaged directions. Drain; cover to keep warm.

Heat 2 tablespoons vegetable oil a large nonstick skillet over medium-high heat. Add beef and marinade; stir-fry 2 to 3 minutes or slightly pink in center. Transfer beef to a bowl.

Heat remaining 2 tablespoons vegetable oil in skillet. Add broccoli, bell pepper, and onion; stir-fry 2 minutes. Add zucchini; stir-fry 2 to 3 minutes or until vegetables are crisp-tender. Return beef and juices to the skillet; toss to combine. Add cooked udon noodles; gently stir to combine.

To serve, divide mixture among 4 serving bowls, drizzle with additional chili oil, if desired.