Drizzle this mushroom-fortified gravy over your Thanksgiving side dishes.
Heat oil in a medium saucepan over high heat. Cook turkey neck, heart, and gizzard, stirring occasionally, until browned, about 10 minutes. Reduce heat to medium. Add onion and garlic. Cook, stirring often, until starting to soften, about 4 minutes. Add mushrooms. Cook for 4 minutes. Add stock. Bring to a simmer. Reduce heat to low, and simmer until liquid reduces by half, 45 minutes to 1 hour.
Combine cornstarch and thyme in a bowl. Strain gravy through a large colander, pressing vegetables with a wooden spoon; discard solids. Strain liquid through a fine sieve, and whisk into cornstarch-thyme mixture. Return gravy mixture to saucepan over high heat, and bring to a boil. Reduce heat to medium low, and simmer, whisking constantly, until thickened and starch flavor is cooked out, 2 to 3 minutes. Season with 1/2 teaspoon salt. Serve warm.