Begin by roasting the corn: Preheat the oven to 400 degrees. Peel the husks off the corn, top each cob with a teaspoon of butter, and wrap each one in foil. Roast for thirty minutes. Remove corn from cobs.
In a small jar, shake together all the Lemon Vinaigrette ingredients.
Fill 4 bowls with a layer of lettuce. Top with the tuna, roasted corn, cucumbers, tomatoes, carrots, red onion, avocado, and lemons. Drizzle on as much vinaigrette as you.