Soak the cashews in hot water for 20 minutes then drain and rinse. Add them to a high-powered blender along with filtered water, plain unsweetened dairy free yogurt, tapioca starch, coconut oil, nutritional yeast, vegan lactic acid (or lemon juice), and kosher salt until completely smooth. This could take a couple of minutes depending on the power of your blender.
In a small saucepan over medium heat, add 1/2 cup of water and the agar agar powder. Whisk together and heat up until bubbles start to form and it slightly thickens.
Pour the cheese mixture into the saucepan and whisk thoroughly to combine with the agar mixture.
Switch to a silicone spatula and stir around the edges folding the cheese mixture into itself. It’ll start to thicken as you continue to stir in this motion. It’s ready when the cheese starts to form a loose ball and pulls away from the sides of the saucepan. Remove from the heat.
Make an ice bath by filling a large bowl with ice and ice-cold water. Add a hefty pinch of kosher salt and give it a quick stir. Use a cookie scoop to scoop the cheese into balls and release them into the ice bath brine. Continue with this process until you've used up all the cheese.
Cover and place the mozzarella balls in the brine in the fridge for a couple of hours before enjoying. The cheese will continue to harden as it chills and will be easier to slice. To store, transfer the mozzarella in the brine to an airtight container and store it in the fridge for up to 5 days.