In a pot, add 1 cup water and brown sugar and bring to a boil. Stir and once all the sugar dissolves take it off heat. Set aside.
In a high speed blender, add watermelon, jalapeno, cold water, mint and lemon juice and blend until it gets all smooth. You can do it in parts also if your blender in not that big. Strain. Add sugar syrup and stir. Taste and adjust lemon juice or sugar if needed. Chill for few hours before serving.
Stir before serving. Serving with ice.
Recipe by Naive Cook Cooks at https://www.naivecookcooks.com/jalapeno-watermelon-lemonade/