Remove green skin and the hard white part of Watermelon. Place the white/lighter red part of the rind into a food processor. Process for a few seconds to make Watermelon Pulp.
Strain most of the liquid from Watermelon Pulp and add 1 cup of Watermelon Pulp to Pressure Cooker cooking pot. Add the rest of the ingredients.
Lock on Lid and Close Pressure Valve. Cook at High Pressure for 20 minutes. Allow all Pressure to release Naturally. Remove lid and simmer for 5 minutes, or until thickened.
Stove Top Method
Add all ingredients, plus 1/4 cup more Watermelon Rind Juice to a Saucepan. Bring to a boil and then turn to low and simmer for one hour, or until thick.