Heat sesame oil in a large skillet or wok over medium-high heat. Add the ground chicken and cook, breaking it up with a spoon, until browned and cooked through. Drain off any excess grease.
Add the chopped onion to the skillet and cook until softened, about 3-4 minutes. Stir in the minced garlic and grated ginger and cook for another minute until fragrant.
Add the broccoli florets and sliced carrots to the skillet. Stir-fry for 5-7 minutes, or until the vegetables are tender-crisp.
In a small bowl, whisk together the soy sauce and rice vinegar. In another small bowl, mix the cornstarch with water to create a slurry. Pour the soy sauce mixture into the skillet, then stir in the cornstarch slurry. Cook, stirring constantly, until the sauce thickens.
Serve the ground chicken and vegetable mixture over cooked rice. Garnish with sesame seeds, if desired.
Notes
This recipe is easily adaptable. Feel free to add other vegetables like bell peppers, snap peas, or water chestnuts. Adjust soy sauce and rice vinegar to your taste.