Steam the unpeeled potatoes until they are just tender when pierced with a fork, but not mushy. If they are very small, leave them whole, or, when cool enough to handle, cut them in half or quarters with a very sharp knife, taking care not to pull off the skin. Place them in a large bowl, or on a serving platter surrounded by the green pepper rings. Slice the eggs crosswise, but remove and discard two of the yolks. Arrange the slices over the potatoes. Add the onion rings and olives, and sprinkle the salad with the parsley. In a small bowl, combine the dressing ingredients. Pour the dressing over the salad. Either serve the salad as is, or toss it gently. The salad may be served at room temperature or chilled.