Soak the cashews in water for at least 4 hours or overnight.
Drain and rinse the cashews.
Add the cashews, water, lemon juice, and salt to a high-speed blender and blend until smooth and creamy.
Transfer the mixture to a saucepan and sprinkle the agar agar over the top.
Whisk the mixture and bring it to a boil, then reduce the heat and simmer for 5-10 minutes, stirring frequently, until the mixture thickens.
Pour the mixture into a mold or container and refrigerate for at least 2 hours, or until firm.
