Cut the watermelon off the rind (doesn't have to be triangles).
Spray the pieces down with a little olive oil (optional) and put just the tiniest bit of salt on one side. Repeat with pepper.
Prepare a grill pan on medium heat. You can Pam the grill pan or if you have an outdoor grill....I don't know, I have never had one!
**Caution** they continue to let liquid out as they cool so a) conserve the liquid, it's tasty and b) if you put this in a salad right away it will get soggy.
Note on lettuce: The darker lettuce may contain iron, it's better for you than any of the light green stuff.
Finally, add something crunchy for texture. I like a soynut/dried fruit/walnut mix.