Method
1. Salt the Chicken
Pat the chicken thighs dry and season all over with the kosher salt. Leave it on the counter while you do the next step—even 15 minutes of contact makes a difference in texture.
2. Load the Slow Cooker
In a 6- to 8-quart slow cooker, stir together the hoisin, oyster sauce, tomato paste, chopped garlic, ginger, black vinegar, garlic powder, red pepper flakes, and the scallion whites. Add the salted chicken and turn to coat. Add no liquid—the thighs will release plenty.
3. Cook
Cover and cook on HIGH for 2 hours, until the chicken shreds easily. It holds fine on WARM for a few hours after.
4. While Chicken Cooks
Toss the sliced cucumbers with the rice vinegar and sugar. Let sit while everything else finishes. This is the acid and crunch that keeps the dish from going flat.
5. Fry the Garlic
Shortly before chicken finishes, heat the neutral oil in a small skillet over medium. Add the sliced garlic and fry, stirring, until pale gold—2 to 3 minutes. Pull off the heat immediately and strain, saving both the chips and the oil. They keep browning after they leave the pan, so stop early.
6. Skim and Reduce
Tong the chicken onto a sheet pan. Let the liquid settle 15 minutes, spoon off the fat cap, then pour into a saucepan and boil hard until syrupy and reduced by about half, 10 to 15 minutes.
7. Sauce and Broil
Heat the broiler. Shred the chicken with two forks right on the sheet pan, pour over the reduced sauce, and toss to coat. Spread in an even layer and broil 3 to 4 minutes, until the edges darken and crisp. Watch it—the hoisin sugars go from caramelized to burnt fast.
8. Finish
Off the heat, drizzle with the toasted sesame oil and a spoonful of the garlic oil. Taste and add more black vinegar, salt, or red pepper flakes—it usually wants more vinegar than you expect. Top with the garlic chips, scallion greens, and sesame seeds. Serve with the pickles.