Prepare and Sear the Carcass: Break down the turkey carcass so it fits into your stockpot. Heat a splash of olive oil in the stockpot over medium-high heat. Add the carcass and sear it until browned on all sides, about 5-7 minutes. Remove and set aside.
Sauté the Vegetables: In the same pot, add the onion, carrots, celery, and garlic. Sauté for about 5 minutes, or until they start to soften and pick up some color.
Deglaze and Add Carcass: Return the seared carcass to the pot with the vegetables.
Add Herbs, Seasoning, and Water: Add the bay leaf, thyme, parsley, and peppercorns. Cover with cold water.