Add the grilled corn, queso fresco, Parmesan cheese, mayonnaise, salsa, cilantro, onion, salt, and diced jalapeños (optional) to a medium mixing bowl. Fold together with a spoon or spatula until all ingredients are just combined. Do not overmix! You want the queso crumbles to be mixed in evenly, but still maintain their shape.
1 cup crumbled queso fresco, ½ cup Parmesan cheese, ¼ cup mayonnaise, ⅓ cup salsa, 1 - 2 tbsp chopped cilantro, 1 heaping tbsp finely diced sweet onion, ⅛ tsp salt, Finely diced fresh or pickled jalapeños to taste