1. Begin by removing the kernels from the cob. The easiest way to do this is to lay the corn down long ways on the cutting board and use a sharp knife to cut the kernels off. Continue to do this by rotating the cob and laying it on the flat side for stability.
2. Once the corn is removed from the cob, put it in a large bowl with the black beans, avocado, feta, red onion, and cilantro. Toss until combined. In a small bowl, combine all of the dressing ingredients and whisk until emulsified. Pour half the dressing over the ingredients and toss until everything is coated. Taste and add more dressing as desired. Serve immediately.