1: Shell the boiled peanuts. Weigh out 1¼ pounds shelled peanuts and snack on any extra. Working in batches if necessary, transfer the peanuts to a food processor and process until smooth, about 1½ minutes. Transfer to a bowl.

2: Combine the koji and 3 tablespoons plus 1 teaspoon of the finishing salt in a glass bowl and gently massage together with your fingertips until well mixed. Fold the mixture into the peanuts and stir to combine completely. If the mixture is too dry and crumbly, add bottled water 1 tablespoon at a time until the mixture is pasty and releases a small amount of clear liquid when pressed.

3: Place the mixture in the freezer bag, pushing it all the way down to the bottom to eliminate as much air as possible. Sprinkle the remaining tablespoon of finishing salt over the top of the mixture and fold the top of the bag over it, but don’t seal the bag. Place the bag in the stoneware crock and put at least 2 pounds of weight on top (a 1-quart canning jar filled with water works well). Put the crock in a cool, dark area where the temperature won’t exceed 75°F and let ferment for about 6 months. Taste the miso to see if it’s ready; it should taste quite salty, a little sweet, and pleasantly savory, like a nice aged cheese.

4: Remove the clear liquid that has formed on top of the miso. (There will be only about 2 tablespoons, but you can refrigerate it for up to 6 months to use as a salty seasoning, if you like.)

5: Working in two batches, transfer the miso to a food processor and process until smooth, about 2 minutes. Transfer the miso to a nonreactive container with a lid. Place a piece of wax paper directly on top of the miso to help prevent a skin from forming, then place the lid on the container and refrigerate. Tightly covered, the miso will keep for up to 6 months in the refrigerator. Check the wax paper occasionally and replace it if it has absorbed some of the liquid and become soggy.