In a skillet, heat oil over medium heat. When hot, add the onions. Sauté them for 3-5 minutes or until they're soft and translucent. Remove them from the heat and let them cool.
Put some parchment paper into a loaf pan; set it aside.
Get a large mixing bowl and to it, add all of the turkey meatloaf ingredients from the ground turkey to the thyme. (Basically, everything but the ketchup and balsamic.) Mix it until everything is well blended, then pour the mixture into your loaf pan. Gently tap the loaf pan flat on the countertop to ensure it's set into the pan and, with a spatula, lightly press down on the top of the meatloaf.
Pop the meatloaf into the fridge to set for 30.
When 30 minutes are up, take the meatloaf out from the fridge and set it on the counter to come to room temp. This should only take about 15 minutes.
Position a rack in the middle of the oven and preheat to 350º F.
Mix the ketchup and balsamic glaze in a small bowl, then spread it evenly over the top of the meatloaf with a basting brush or spoon.
Transfer the meatloaf to the oven and bake for about 40 minutes or until the ground turkey reaches an internal temperature of 160-156º F.
Take the meatloaf out of the oven and let it sit for about 10 minutes before serving.
Garnish with chopped fresh parsley for a nice pop of green!