Combine the cashews, 1 cup water, the mashed potato, 2 tablespoons plus 2 teaspoons tapioca starch, the coconut oil, black truffle salt, tahini paste, yeast, lactic acid, mustard, and truffle oil in a strong blender or food processor to make Brie “milk.”

Blend the ingredients on low and gradually increase to top speed until the mixture is completely smooth. Depending on your machine, this could take 1 minute to 6 minutes. (Stop every minute or so to scrape down the side of the container if needed.)

If you are using quick-set agar powder, add it to the blender without extra water and blend until smooth, then skip to step 6. Otherwise, place the agar powder in a medium-size pot or pan. Use a fork to whisk the ½ cup water into the agar. Let the mixture sit for 1 minute. The agar may thicken a little.

Vigorously stir the mixture over medium heat for 5 minutes. The powder will dissolve completely, and the mixture should bubble, boil, and froth a little. When it thickens to look like dense and slightly glossy applesauce, it’s ready.

Quickly and very carefully scrape the agar mixture into the full blender before it solidifies. Use caution! Hot agar is painful and difficult to remove if it drips on your skin. Blend the mixture until thoroughly combined, about 1 minute.

Pour the cheese mixture into a clean pot or pan. Stir it frequently over medium heat as the mixture simmers and starts to change from thin to lumpy.

Stir the mixture continuously in order to eliminate the lumps and create a smooth texture. It will thicken dramatically as it heats. Stir, fold, and knead for 5 to 7 minutes to fully activate the agar powder and cook the tapioca.

Lower the heat if you feel any sticking in the pan or if the blend “spits” too much. Turn off the heat when the Brie is shiny and coats the spoon thickly—you may even see stretchy strings.

Pour the hot Brie into the form or container and allow it to cool, uncovered, in the refrigerator. It should firm up in about 30 minutes, depending on the brand and strength of the agar powder. (Note: You can speed up the cooling process with 15 to 20 minutes in the freezer—just don’t forget it there!)

Once the cheese is firm, use a silicone scraper, if needed, to gently remove the Brie from the form.

Spread the remaining 1 tablespoon tapioca and the white pepper on your work surface and blend evenly.

Very gently roll the Brie wheel (it is tender), covering the top and sides. When covered, it will look powdery smooth, just like Brie.

Pat off the excess powder. It’s ready to plate and serve!

Store your Brie in a dry, covered container in the refrigerator. It will remain most firm in the first 2 days but is good for about 1 week.