In a large pot, bring water to a boil. Add corn and boil for 3 minutes. Remove corn to a plate and cool just enough to handle. When the corn is cool, cut the kernels off the cob, cutting close to the cob, and place them in a large bowl. You should have approximately 4 cups of corn.
Add the tomatoes, green onions, cilantro, and feta to the corn.
In a small bowl, whisk the olive oil, vinegar and garlic. Pour over the salad and toss well to combine. Season with salt and pepper, to taste. Cover and chill for 15-30 minutes before serving.