Preheat the oven to 450F. Place wings in an even layer in a Roasting Pan and toss with 1 Tbsp. oil. Roast, stirring halfway, until the wings are deep golden brown, about 55 minutes. Remove from oven and let cool.

Heat a Stock Pot over medium-high heat. Add the remaining 1 Tbsp. oil and heat until the oil moves freely in the pan, about 30 seconds. Add the onion, cut side down, and cook, undisturbed, until deeply browned, about 4 minutes.

Add the celery, carrots, garlic, peppercorns, thyme, parsley stems, bay leaf and wings to the pot and stir to combine. Pour in 4 ½ quarts (18 cups) water to cover the ingredients.

Pour 2 cups of water into the Roasting Pan and using a Wooden Spoon, scrape any brown bits sticking to the bottom of the pan. Add that liquid to the Stock Pot. Bring everything to a simmer and reduce the heat to low to maintain a gentle simmer.

Skim off any impurities that rise to the top and discard. Season with a big pinch of salt. Continue to simmer the stock for 4 ½ hours, skimming as impurities rise to the surface.

Strain out the solids and the stock is ready to use. If you’re not using immediately, place Stock Pot in an ice bath to quickly cool to room temperature. Chill completely in the refrigerator for at least 4 hours or overnight. Remove and discard any fat that solids on the surface if desired.