What you need:
1 cup tomatoes, diced
1 cup watermelon, diced
1/4 red onion, finely diced
1 jalapeno pepper, finely diced, seeds removed unless you like it really hot
2 tablespoons diced cilantro
salt
1 freshly squeezed lime
a few dashes of hot sauce
What you do:
1. Cut up tomato and watermelon into chunks of about 1 cm.
2. Add everything else and let it sit for at least an hour. Have a taste and see if you need to adjust add more salt or hot sauce.
Ready to go!