Preheat oven to 400 degrees F (200 degrees C). Combine corn and oil in a shallow pan.
Bake in the preheated oven, stirring once or twice, until lightly browned, 8 to 10 minutes. Cool.
Mash 1 avocado and coarsely chop the remaining one.
Combine corn, mashed avocado, chopped avocado, tomato, lime juice, onions, garlic, jalapeno peppers, salt, and cumin in a bowl; cover and chill for 24 hours.