For Fresh Corn on the Cob: Remove the husks and clean the corn. Lightly brush the corn with oil and place on a hot grill or in a hot skillet or grill pan. Rotate the corn every 1-2 minutes, as you see charring and blistering occur. When corn is fully blistered, remove, let cool until it can be easily handled, and cut off the kernels.
For Frozen Corn Kernels: Place in a skillet and let them thaw for a few minutes. Once thawed (but before they've started blistering) add oil and stir. Let the corn sit (without stirring) for 2-3 minutes, or until they've started to blister. Give the skillet another toss, then let sit and blister another 1-2 minutes.
Make the Salsa
Dice all other fruits and veggies and combine in a bowl with the blistered corn kernels. Add chopped cilantro, squeeze the lime, and stir to combine. Season with salt to taste.