Make the berry swirl: Combine the sugar and 2 Tbsp. water in a saucepan. Bring to a boil over medium heat. Boil, swirling the pan occasionally, until the mixture is amber, about 6 min.
Immediately and carefully add the berries, miso, and lemon juice to the saucepan. Stir to incorporate. Return to a boil, and cook until it thickens, stirring occasionally, about 10 min.
Set a fine sieve over a heatproof bowl, and strain the berry mixture through the sieve, using a spoon to press on the solids and release all the fruit juice and puree. Cool completely in the refrigerator, about 1 hr.
Make the ice cream: Add the cashews, coconut cream, cashew milk, sugar, vanilla, and salt to a blender. Puree on high, scraping down the sides of the blender if necessary, until mixture is very smooth and fluffy, 2 min.
Pour the ice cream mixture into a shallow, freezer-safe 8-by-8-in. baking dish. Stir the chilled berry mixture, then drizzle it in lines over the top of the ice cream. Using a small offset spatula or a butter knife, make figure-eight motions through ice cream base until the berry mixture is just swirled (don't overdo it). Cover, and freeze at least 4 hr. Let soften at room temperature, 5 to 10 min. before serving. (Store in the freezer for up to 1 month.)
Recipe by Laura Rege.