Step 1

Preheat oven to 450°. Toss wings in a large cast-iron skillet with 2 Tbsp. oil until coated. Roast, tossing halfway through, until golden brown and starting to crisp, 25–35 minutes.

Step 2

Remove wings from oven and add garlic, shallots, ginger, mushrooms, peppercorns, and remaining 2 Tbsp. oil to pan; toss to coat. Return to oven and roast, tossing halfway through, until wings are deeply browned and crisp and vegetables are browned, 30–40 minutes more.

Step 3

Meanwhile, mash together flour and butter in a small bowl with your fingers or a fork until homogenous. Set beurre manié aside.

Step 4

Remove skillet from oven and set on stovetop over medium-high heat. Add sherry and cook, stirring and scraping up any browned bits with a wooden spoon, until sherry is almost completely reduced, about 2 minutes.

Step 5

Scrape wings and aromatics into a medium pot and add parsley and stock. Bring to a low simmer over medium-high heat. Reduce heat and simmer gently, skimming fat from surface occasionally and turning wings so both sides get a chance to be submerged, until liquid is flavorful, mahogany in color, and reduced by about one-third, 30–40 minutes.

Step 6

Fish out wings; discard. Pour mixture through a fine-mesh sieve into a large measuring glass; discard solids. Rinse out pot and pour turkey mixture back in. Bring to a simmer over medium. Whisking constantly, add reserved beurre manié and whisk until completely incorporated. Simmer, whisking often and skimming any foam from surface, until gravy is thick enough to coat a spoon, 6–8 minutes. Remove from heat and whisk in vinegar and MSG. Taste gravy and season with salt and pepper if desired.

Step 7

Do Ahead: Gravy (without vinegar and MSG) can be made 5 days ahead. Let cool, then cover and chill. Reheat over medium until simmering, then add vinegar and MSG.