2. Chop the tail and joint meat into 1/2 inch pieces and reserve the whole claw meat for garnish.
3. In a medium pot of boiling salted water, cook the corn until tender, about 10 to 15 min. Let cool and cut the kernels from the cob.
4. Toss the lobster meat, corn, mango, red pepper, onion, celery, and cilantro in medium mixing bowl and season with salt and pepper.
5. To make the dressing, puree the watermelon, grapefruit juice, vinegar and Dijon mustard in a food processor or blender for 1 minute. With the motor running, slowly add canola oil. (This can be made in advance and stored in the refrigerator for up to 3 days.)
6.Add about 1/2 cup of dressing to salad mixture, season with salt and white pepper and refrigerate for 2 hours. (Reserve the leftover dressing for another use.) Serve the salad over shredded iceberg lettuce on individual plates and garnish with a lobster claw and whole cilantro leaves.