Prepare your ingredients: Slice the yellowtail, chop the onion, jalapeño, cilantro, and jicama, cube the avocado, and shave the corn kernels from the cob.
Start your base: Add the yellowtail to a medium bowl, followed by the red onion.
Build the salad: Add in the jicama, corn, avocado, jalapeño, and cilantro.
Season + mix: Drizzle with olive oil and lime juice, then season with salt and pepper. Gently stir to combine, being careful not to mash the avocado.
Serve immediately: Spoon into a shallow serving dish or individual bowls and enjoy!