To make the vinaigrette, put the tomatoes, vinegar, and garlic in a blender or food processor. Blend or process until relatively smooth, 1 minute. With the machine running, slowly drizzle in the olive oil until the mixture thickens, 1 to 2 minutes. Then add the parsley, salt, and pepper, and process just until the parsley is chopped.
For the salad, layer the ingredients, in the order listed, in a salad bowl or on individual plates. Drizzle on the vinaigrette.
Tip: You can make the vinaigrette up to 2 days ahead and the salad a few hours ahead. Keep them refrigerated until you are ready to eat, and pour on the dressing just before serving.