In a large, heavy-duty stockpot, combine 1 gallon of water, Kosher salt, sugar, sliced oranges, lemons, limes, smashed garlic, coriander seeds, and fresh thyme.
Place the pot over medium-high heat. Bring the vibrant mixture to a gentle simmer, stirring frequently until the Kosher salt and sugar have completely dissolved (about 5-10 minutes).
Remove the pot from the heat. Use a wooden spoon to gently muddle and press the citrus slices against the side of the pot to release extra essential oils from the peels. Let it cool slightly at room temperature.
Pour the citrus concentrate into your designated brining container (a massive pot or a heavy-duty brining bag). Immediately pour in the 1 gallon of ice water to drop the temperature fast. Wait until the liquid is entirely ice-cold before proceeding.
Submerge your fully thawed, raw turkey into the chilled liquid, breast-side down. Make sure the entire bird is covered.
Transfer to the refrigerator and let the bird soak for 12 to 18 hours to absorb those bright, zesty flavors.
Remove the turkey from the liquid and discard the brine. Pat the bird incredibly dry inside and out with paper towels before roasting for perfectly crisp skin.