The day before you want to cook the chicken, season the chicken thighs and legs generously with salt and let it sit out for 30 minutes in a large bowl.
Stir 4 teaspoons fine sea salt into the buttermilk to dissolve. Place the chicken in the buttermilk and put into the fridge.
Take the chicken out from the fridge an hour before you plan to cook it. Preheat the oven to 220 C, with a rack set in the center position.
Remove as much buttermilk as you can from the chicken and smoker over the marinade ingredients.