Preheat oven to 375° F (190° C). On two parchment-lined baking sheets, spread cheese equally into four 6-inch circles. Bake until golden brown, about 4 to 5 minutes. While still warm, carefully lay cheese circles over the backside of bowls to shape. Allow to cool.
In a large bowl, whisk together vinegar, yogourt, salt and pepper. Toss lettuce, cucumbers and tomatoes in dressing. To serve, set a Parmesan bowl in the centre of each of 4 plates and fill each bowl with salad.