These slow cooker turkey wings are first braised until tender and then broiled to a crispy finish.
Using paper towels, pat the turkey wings dry and season generously with salt and pepper. In an extra-large skillet, heat 1 tablespoon of the oil until shimmering. Add half of the turkey wings to the skillet and cook over moderately high heat until browned all over, about 7 minutes. Using tongs, transfer the browned turkey wings to a 6-quart slow cooker. Repeat with the remaining wings and oil. Add the wine to the skillet and cook over moderately high heat for 1 minute; scrape up any browned bits with a wooden spoon, then pour the wine over the wings.
In a medium bowl, whisk the soy sauce with the brown sugar and sesame oil. Pour the soy sauce mixture over the wings. Add the trimmed scallions, garlic, ginger, cinnamon stick, star anise and crushed red pepper flakes to the slow cooker, then cover and cook on high for 3 1/2 to 4 hours (or about 7 hours on low), until the wings are very tender but not falling apart.
Preheat the broiler. Place an oven-safe wire rack over a rimmed baking sheet lined with aluminum foil. Using tongs, arrange the turkey wings on the wire rack in a single layer. Strain the cooking liquid into a liquid measuring cup and skim off the fat. (You will have about 1 1/2 cups of cooking liquid.)
Lightly brush the wings with 1 tablespoon of the cooking liquid and broil the wings 4 to 6 inches from the heat for about 8 minutes, rotating the baking sheet front to back once about halfway through, until the wings are deep brown and beginning to crisp.
Whisk the rice vinegar into the reserved cooking liquid. Transfer the wings to a serving platter. Garnish with the sliced scallions and toasted sesame seeds. Serve, passing lime wedges and the extra cooking liquid at the table.