Pat the chicken thighs dry with paper towels. Season both sides evenly with the kosher salt. Arrange them skin-side up in a single layer in the slow cooker insert.

In a small bowl, whisk together the hoisin sauce, soy sauce, rice vinegar, grated ginger, minced garlic, and sesame oil until smooth. Pour the mixture evenly over the chicken, making sure some gets underneath each thigh.

Cover and cook on LOW for 6 to 7 hours, or on HIGH for 3 to 4 hours, until the chicken is fall-off-the-bone tender and registers 165 degrees F in the thickest part. The sauce will look thin at first but will thicken and reduce as it cooks.

Transfer the cooked chicken to a plate. Pour the cooking liquid into a fat separator or skim off excess fat with a spoon. Return the defatted sauce to the slow cooker, set to HIGH, and simmer uncovered for 10 to 15 minutes until slightly thickened and glossy.

For crispy skin, place the cooked chicken thighs on a foil-lined baking sheet and broil 6 inches from the heat for 3 to 4 minutes until the skin is crackling and deep golden. Watch closely to prevent burning.

Spoon rice into shallow bowls. Nestle the chicken on top, ladle the reduced sauce over everything, and finish with sliced scallions and toasted sesame seeds.