Dissolve the arrowroot powder (or tapioca starch) in 50ml soy milk, leave to rest.
In a small saucepan combine the rest of the soy milk, the soy cream, sugar, agave syrup and vanilla bean seeds, bring to an almost boil, add the starchy soy milk mixture and cook constantly stirring until thickened. Take of the heat, let cool to room temperature, transfer into the fridge overnight.
Freeze in your ice cream maker according to manufacturer's instructions. Store in the freezer in an airtight container for at least 4 hours or spoon right away.