Cut the corn from the cob into a large bowl. Place 2 cups of the corn into the food processor and pulse until slightly pureed, but still somewhat chunky. Return to the bowl with the remaining corn.
Add the flour, corn meal, onion, cilantro, baking powder, baking soda, and salt and pepper. Stir to combine.
Add the eggs, buttermilk, and butter and stir until just combined.
To make the relish, combine all of the ingredients into a small bowl, except for the avocado. Stir to combine everything. Store in the refrigerator for up to 2 days. Add the avocado just before serving, to prevent browning.
Heat a large skillet over medium heat. Add enough oil to cover the bottom of the pan and heat until it's sizzling hot.
Scoop tablespoons of batter into the hot pan, about 4 or 5 per batch. Do not over crowd the pan. Fry 1-2 minutes per side, until golden brown. Transfer to a paper towel lined dish.
Serve immediately with the relish. Ranch dressing is also yummy on these guys.