Mix and mash the mayonnaise and 1/3 cup of the Roquefort in a medium bowl until the cheese is very finely crumbed. Mix in the vinegar, 1/4 teaspoon salt, and pepper to taste.
Toss the lettuce, cucumber, eggs, carrots and tomatoes together in a large bowl. Add the dressing and toss to coat. Season with salt and pepper. Top with the remaining Roquefort and serve immediately.