Heat olive oil over medium-high heat in a large skillet.
Add celery, broccoli, onion, sweet pepper, and carrots and cook until lightly browned but crisp.
Add garlic and cook for 2 minutes. Remove vegetables from skillet.
Add ground turkey to skillet and cook through, leaving the meat in chunks. Drain if needed.
Add salt, pepper and vegetables back to the skillet and mix.
Combine the cornstarch, water and soy sauce in a separate bowl and whisk until thoroughly mixed. Add to the meat mixture. Cook and stir until the sauce thickens.