Heat olive oil over medium-high heat in a large skillet. Add turkey and onion and season with salt and pepper; cook, breaking up the turkey, until the meat is cooked through and the onion is translucent. Add garlic and cook until fragrant, about 30 seconds. Stir in tomato sauce, maple syrup, soy sauce, cider vinegar, brown sugar, and dijon mustard. Simmer on medium-low until the sauce has thickened slightly, just a few minutes.