Chop the watermelon flesh into small cubes using a sharp knife and cutting board, ensuring all seeds are removed. Measure out 2 pounds of prepared watermelon.
2 pounds watermelon flesh
Transfer the cubed watermelon into a saucepan and add 1/4 cup water. Bring to a gentle simmer over medium heat, stirring occasionally, until the watermelon softens and releases juices, about 10 minutes.
2 pounds watermelon flesh, 1/4 cup water
Use a silicone spatula to mash the softened watermelon into a smooth pulp directly in the saucepan, then pass the mixture through a fine mesh sieve into a bowl to remove any remaining solids and seeds, resulting in a bright red juice.
2 pounds watermelon flesh
Return the strained watermelon juice to the saucepan and add the sugar along with the citrus zest. Place over medium heat, stirring continuously until the sugar dissolves completely and the mixture begins to thicken slightly, about 10-15 minutes. You will see the syrup coat the back of a spoon.
2 cups granulated sugar, 1 tablespoon citrus zest
Increase heat slightly and cook until the jam reaches a viscous consistency, about 5 minutes. The jam should be glossy and thick enough to mound on a spoon without running. Remove from heat and allow to cool slightly.
Transfer the hot jam into sterilized jars or bowls for storage. Let it cool to room temperature before sealing or serving. The final product is a vibrant, translucent red spread with a fragrant, summery aroma.
