Start by preparing the napa cabbage: trim the root end and then slice in half length-wise. Turn cabbage cut side down and slice thinly cross-wise. Weigh the prepared cabbage and add 3.5% salt by weight (see story above for more details). My trimmed cabbage weighed 1 pound 6 ounces to which I added 1 tablespoon plus 1/2 teaspoon canning salt. Massage the cabbage and salt together until the cabbage has wilted and it has released it's moisture. Set aside.
Add the remaining ingredients to a food processor, starting with 2 tablespoons of vinegar, adding more if necessary, to create a pesto-like paste. Add paste to the cabbage and mix well to combine.
Pack into a quart-sized canning jar by adding a small amount of the cabbage mixture at a time and packing down with the back of a large spoon before repeating the process. Run a skewer around the jar to release any air bubbles. Weigh down the cabbage to ensure it is completely submerged under the liquid (see story above for more details).
Set aside to ferment - the time will depend on the temperature of your space along with your taste preferences. Taste it often to decide when it is finished (I let mine ferment for 1 week). Transfer to the refrigerator and eat within a couple of months.
Place all ingredients in a medium mixing bowl and smash together with the back of a spoon. Taste test it by adding a small amount to a piece of plain bread or cracker. Adjust seasoning as desired and do another taste test. To store, form into a log using plastic wrap and store in the freezer until ready to use.
If you need to quickly bring cold butter to room temperature, cut it into 1" pieces and place evenly on a dinner plate. Cook in the microwave in 30 second increments at 20% power. The butter should be soft to the touch but not runny.