Cut the watermelon into 1 inch thick slabs and lightly brush them with olive oil. Place the slabs of watermelon cut side down onto a heated grill and grill for about 2-3 minutes per side or until marked and warm.

Remove from the grill and cut off the rind, then cut into 1 inch cubes. Toss the grilled watermelon with the basil, salt, pepper, and lime juice. Stir in the cubed feta being careful not to break it up.

Drizzle the salad with the balsamic reduction before serving. Salad is best made and eaten the day it is served.