Heat a large skillet over medium heat and add the olive oil.
Add the diced onion to the skillet and sauté for about 3-4 minutes until softened and translucent.
Add the minced garlic to the skillet and cook for another minute until fragrant.
Add the ground turkey to the skillet, breaking it up with a spatula as it cooks. Stir occasionally until it’s fully browned and no longer pink, about 6–7 minutes.
In a small bowl, whisk together soy sauce, water, brown sugar, rice vinegar, sesame oil, and grated ginger.
In another small bowl, mix cornstarch with cold water until fully dissolved to create a slurry.
Once the turkey is cooked through, pour the soy sauce mixture over it and stir to combine.
Bring the sauce to a simmer and cook for about 2–3 minutes.
Add in your cornstarch slurry while stirring continuously until you reach your desired consistency.
If you're feeling adventurous, sprinkle in red pepper flakes at this stage for an extra kick.
Serve your teriyaki ground turkey over cooked rice by dividing it into bowls.
Garnish each bowl with sliced green onions and a sprinkle of sesame seeds.
Serve immediately while hot.