Begin by bringing a large pot of salted water to a boil over medium-high heat. Carefully add the fresh corn kernels and boil for 5–7 minutes until tender but still crisp. Once cooked, drain the corn and transfer it to a bowl of ice water to cool quickly.

In a large mixing bowl, combine the cooled corn with diced cucumber, halved cherry tomatoes, and chopped red onion. Use a wooden spoon to gently fold the ingredients together.

In a separate bowl, whisk together the mayonnaise, sour cream, lime juice, chili powder, salt, and pepper until smooth and well-combined. Make sure to taste the dressing and adjust for seasoning.

Pour the prepared dressing over the vegetable mixture, then use a spatula to toss everything gently until each ingredient is fully coated.

Generously sprinkle crumbled feta cheese and chopped cilantro over the top of the salad. Allow the salad to sit for a few minutes before serving.