Line a shallow bowl or plate with a kitchen towel. Use one hand to hold an ear of corn in place upright atop the kitchen towel. With your other hand, use a knife to cut off two to three rows of kernels at a time by sliding the knife down the cob. Get as close to the cob as you can. Transfer corn to a bowl with the tomatoes, feta, and herbs. If using the chickpeas or beans, add them to the bowl as well.
Add 1/2 teaspoon kosher salt and pepper to taste. Add 4 tablespoons oil and the juice of half a lime. Toss and taste. Add another 1/2 teaspoon salt if necessary and more pepper to taste. If it needs more acidity, squeeze in the remaining lime. If it needs more dressing, drizzle in the remaining 2 tablespoons oil. Toss. Serve immediately.