Roast the corn: Heat grill or griddle to high heat. Spread butter onto corn. Place corn cobs directly on the grill. Grill corn, turning occasionally until cooked and lightly charred on all sides, about 10-20 minutes. I found it helpful to set a cast iron lid on top of the corn to help char and cook it faster. Allow to cool and cut corn off cob and transfer to a large bowl.
Combine the salad ingredients: Add the remaining salad vegetables to the corn. Stir everything together until well combined.
Mix the dressing: In a small bowl, whisk together the dressing ingredients. Add to salad and gently toss to combine. Add additional lime juice and/or salt as needed.
Serve: To serve, garnish with additional cheese and cilantro, if preferred.
Notes
If making the salad ahead of time, store it in an airtight container in the refrigerator. For best results, add avocado and dressing just before serving.