Watermelon is a family favorite from, just eating it or adding it to all kind of things.
One of our favorites is blended watermelon with lime juice. Wow is that refreshing and filling. On a hot summer night that becomes a meal in itself. All you do is fill your blender with cut pieces of watermelon and squeeze the juice of one lime. If you thing it is not tangy enough add another, if you think it is not sweet enough a little honey or raw sugar. Usually we stop with the first step.
I know people who take that to another level by adding muddled fresh mint and rum. Your call but why mess with perfection.
Serious Drinks has some great watermelon treats check them out.