For the chicken:
2 tablespoons gochujang
1 tablespoon rice vinegar
2 teaspoons soy sauce
2 teaspoons toasted sesame oil
1/2 teaspoon sugar
1 cup water
1 1/2 pounds boneless, skinless chicken thighs (about 6 small thighs)
2 tablespoons vegetable oil
1 2-inch piece of fresh ginger, washed and cut into 1/4-inch coins
5 cloves garlic, peeled and lightly smashed
For the kale:
1 tablespoon vegetable oil
1/2 cup cabbage kimchi, chopped
4 ounces kale leaves, thick ribs and stems removed, chopped (5 cups chopped)
3/4 cup water
1/2 teaspoon soy sauce
12 small slider buns or dinner rolls
In a small bowl, whisk together the gochujang, vinegar, soy sauce, sesame oil, and sugar until smooth. Whisk in the water and set aside.
In a 10-inch pot or Dutch oven, heat the oil over medium-high heat. Working in batches, brown the chicken thighs and set aside on a plate.
Pour the gochujang mixture into the pot and stir, scraping up any browned bits from the bottom. Add the ginger and garlic, followed by the chicken and any accumulated juices. Arrange the chicken in a single layer in the pot and bring mixture to a boil. Lower heat, cover and let simmer for 30 minutes, turning chicken halfway through cooking. Remove from heat and let sit, covered, for 15 minutes.
Meanwhile, make the kale. In a large skillet with a lid, warm the oil over medium-high heat. Add the kimchi and stir-fry for about 30 seconds, until hot and fragrant. Add the kale, water, and soy sauce, and stir to combine. Bring to a boil, then lower heat, and cover. Simmer covered for 30 minutes, or until kale is very tender. Taste and add more soy sauce if needed. (If making ahead, kale mixture can be covered and refrigerated at this point.)
Transfer the chicken thighs to a bowl and use two forks to shred meat. Pour 1/4 cup of the braising liquid over the meat and mix. (If making ahead, chicken can be covered and refrigerated at this point. Reheat before assembling sliders.)
To assemble, place a sheet pan in the oven and preheat to 350°F. Arrange slider buns cut-side down on preheated sheet pan and bake for 3 to 5 minutes, until lightly toasted. Spread mayonnaise on the bottom bun and top with the chicken, followed by the kale mixture and top bun. Repeat with remaining buns. Serve immediately.