Preheat grill to medium high heat. Coat corn with olive oil and grill to desired degree of doneness. (Go here if you have never grilled corn). Allow corn to cool and cut kernels from cobs.
Add cilantro, olive oil, and lime juice to a blender and puree until dressing is smooth. Add salt (up to 3/4 teaspoon) and pepper to taste and pulse until combined. Add salt until it tastes delicious. Add more lime juice if you need to. Set aside. You could easily make this ahead of time and keep it in the fridge.
Combine corn, tomatoes, and mozzarella in a large bowl. Drizzle with enough dressing to coat (you may have extra) and gently stir to combine. Add avocado and stir even more gently. Chill salad for at least 15 minutes and up to 4 hours before serving.