Removed corn husks, discard.
In a large bowl, place fresh corn stalk vertically. Using a knife, shave the corn kernels from top to bottom. You can also hold the corn stalk and shave it in your hand and have the kernels land in the bowl below. The stalk is hard below the kernels and you won't want to get too much of that in the bowl. This is pretty easy if you've never done it before.
Heat oil in skillet oven medium high heat.
Add fresh corn kernels or frozen corn kernels to skillet. Toss every 2 minutes or until the corn is well charred all over (about 10 minutes). Remove from heat; set aside.
In a large bowl, combine mayo, sour cream, cilantro, green onions, salt, pepper, jalapeno, diced onion, lime juice, and garlic. Stir to combine well.
Pour corn into large bowl and toss with wet ingredients.
Carefully stir in crumbled fete or Cotija cheese.