Heat a large skillet over medium-high heat. Add turkey and stir to break it apart. Sprinkle with garlic powder, salt and pepper, stir. Cook until no longer pink, covering the pan occasionally. Once it’s cooked through, drain the fat and remove the turkey to a plate.
Replace the pan on the burner and add the oil. Add the broccoli and onion and cook, covered but stirring often, until crisp-tender, about 4-5 minutes.
While the vegetables are cooking, stir together the water, soy sauce, brown sugar, ground ginger and cornstarch in a small bowl or measuring cup.
Add the sauce to the cooked vegetables and cook until it boils and thickens (1-2 minutes). Add the ground turkey back to the pan and stir to warm through and coat with sauce.