Brush the corn with melted butter and sprinkle lightly with salt.
Grill over medium-high heat for 10-12 minutes, turning for even browning. Use a sharp knife to remove the kernels from the cob. Cool slightly before adding to the remaining ingredients.
In a medium bowl, whisk together the dressing ingredients. Begin with 1/2 tsp of garlic salt and red pepper flakes, then adjust to your taste.
If serving chilled, toss the grilled corn, cherry tomatoes and red onion with the dressing. Cover and chill.
Peel and cube the avocado mixing into the salad just before serving.
If serving immediately, toss all of the ingredients together and serve at room temperature.