Make pesto by mixing pesto ingredients with a mortar and pestle until combined. Alternatively, you can pulse the ingredients together in a small food processor or in a blender to combine. Set aside.
Add cubed honey dew and watermelon to a platter or salad bowl and sprinkle with salt and mix. Then, add cubed feta and drizzle the pesto over, toss and taste - season with more salt if needed. Garnish with fresh basil.