¼tspkosher salt (Diamond Crystal; use half for table salt)
Gather all the ingredients.
In a small bowl, add 4 Tbsp homemade ume miso and 2 pieces of plums from the ume miso. With a pair of scissors, cut the ume into small bits and discard the seeds.
Prick the chicken skin with a fork (so the flavor sinks in).
Season both sides of the chicken with salt.
Put the chicken in a plastic bag and add the ume miso. Knead the chicken well from outside the bag. If you're not using a plastic bag, use a clean hand to knead the chicken so the flavors will go deep into the meat.
Remove the air and seal the bag. Marinate for at least 6 hours, ideally overnight, up to 24 hours but not more (as it gets too salty).
Line the baking sheet with foil and spray/brush with oil. Place the chicken on the baking sheet, skin side up.
Bake at preheated 400ºF (200ºC) oven for 20-25 minutes. Then change to broiler setting and cook for 5 minutes until the chicken are nicely browned and charred. Serve immediately.
You can store the leftovers in an airtight container and keep in the refrigerator for up to 4 days and in the freezer for 1 month.