Carefully pull back the corn husks just far enough to remove most of the silk. Soak in salt water for 10 minutes. Cook on grill until kernels are tender...about 20 minutes. Cut the corn off the cob then scrape the cob with the back of your knife to get the juices. Set aside and let cool. Slice the tomatoes in half. Rinse and drain the black beans. Chop the cilantro.
Make the dressing in a separate bowl and whisk to combine.
Combine all ingredients together and allow time to sit (10-15 minutes) so the flavors can blend.