Mix all the ingredients and refrigerate until needed.
Preheat the oven to 200°C.
Place the tomatoes on a baking sheet, cut side up. Drizzle with olive oil, season with salt and pepper and roast for 10 minutes. Remove from the oven and leave to cool.
Slice each goat's milk cheese roll into 5-6 slices. Using a cookie cutter slightlybigger than the cheese slices cut out rounds from the bread.
Place the bread on a baking sheet with the cheese on top. Cover with clingfilm and refrigerate until needed.
Arrange the lettuce leaves, baby marrows, mushrooms and celery on a salad platter.
Arrange the tomatoes on top and surround with the onion rings. Just before serving grill the bread and cheese rounds for 10 minutes or until the cheese begins to melt.
Arrange the toasted bread and cheese rounds on top of the salad, drizzle with the vinaigrette and serve immediately.