Preheat your grill to medium-high heat and grill the corn for about 10-12 minutes, turning occasionally until tender and slightly charred.
Once cooled, remove the kernels from the cob and place them in a large mixing bowl.
Add diced cucumber, finely chopped red onion, and fresh cilantro to the bowl with the corn kernels and mix well.
In a separate bowl, whisk together Greek yogurt, mayonnaise, minced garlic, lime juice, chili powder, salt, and pepper. Pour over the corn and cucumber mixture and toss to coat.
Refrigerate the salad for at least 30 minutes before serving to allow flavors to meld.
Before serving, taste for seasoning and garnish with additional cilantro leaves and chili powder if desired.
Scoop servings onto plates or into bowls and enjoy!