Mix watermelon, cucumber, bell pepper, basil, parsley, vinegar, shallot, oil and salt in a large bowl. Puree 3 cups of the mixture in a blender or food processor to the desired smoothness; transfer to another large bowl. Puree another 3 cups and add to the bowl. Stir in the remaining diced mixture. Serve at room temperature or chilled.

Tip: Melon selection & storage: Look for symmetrical unblemished melons, without flat sides, that have a creamy yellow spot on the bottom indicating ripeness. At 92% water, this fruit should feel heavy when you heft it. Precut melon flesh should be dense, firm and appear moist. Store in the refrigerator for up to a week or keep in a cool, dark spot. Cover the cut surface of melon with plastic wrap and refrigerate.

MAKE AHEAD TIP: Cover and refrigerate for up to 1 day.