Heat the oil in a cast iron or heavy-bottomed pan over medium-high heat.
Once the oil is hot, pour the corn into the pan and smooth it into a flat layer. Cook for 6 to 8 minutes, stirring only a few times. You want to give the corn enough time to get a nice char on it before stirring. Remove the corn from the pan and place it in a large bowl.
Add the red onions to the hot pan and sauté, again stirring as little as possible. Cook for about 3 to 5 minutes and then remove and add to the bowl with the corn.
Add the mayo, cilantro, lime juice, salt, and pepper. Stir well.
Place the corn salad into a serving bowl and top with cotija cheese and sprinkle with paprika.
Notes
Store in an airtight container in the fridge for up to 4 days.