In a Medium Sized saucepan, combine agave or maple syrup, almond milk, coconut milk. corn starch and sea salt. Heat over medium-high heat while whisking. You are going to heat until it's thickened and bubbling. This should take 3-4 minutes. Place in fridge until completely cool before going to the next step.
Place watermelon and mint into a high powered blender. Blend on high for 30 seconds to liquefy the watermelon. I used about 3-4 cups of watermelon to get the desired about of 2 1/2 cups of watermelon juice.
Strain the watermelon juice to ensure a consistent product.
Place watermelon juice, coconut milk mixture, and vanilla extra into an ice cream maker. Follow the instructions of your make to make the ice cream.
After the ice cream thickens up, place in a loaf pan or airtight container and place into the freezer to set up. This should take a few hours. Once set, scoop & enjoy. I like to garnish with a sprig of mint.