Bring a small pot of water to a boil. Add the corn kernels and blanch for 1 minute. Drain and set aside.
In a medium bowl, combine the onion, jalapeño, lime juice, vinegar, and a generous pinch of salt.
Use a paring knife to carefully make 1/4-inch thick slices through the avocado flesh without piercing the skin. Rotate the avocado 90 degrees and slice again, to create 1/4-inch squares. With the avocado in the palm of your hand, slide a large metal spoon between the skin and flesh and gently scoop out the squares.
Add the avocado pieces, corn kernels, and cilantro to the onion mixture. Add the olive oil and another pinch of salt and stir gently. Season to taste, adding more salt or lime juice as needed.
nutrition information (per serving):
Photo: Scott Phillips