Place the potatoes and fresh lemon juice in a medium saucepan, covering them with cold water.
Add salt, cover, and bring to a simmer over low heat.
Cook for about 15 minutes or until the potatoes are tender when pierced with a knife.
Drain and let them cool slightly.
Peel and cut into thin slices.
In a small bowl, whisk together the extra-virgin olive oil, sherry vinegar or red wine vinegar, salt, and freshly ground black pepper.
In a shallow serving bowl, arrange the potato slices in layers.
Drizzle each layer lightly with the vinaigrette, seasoning with salt and pepper.
Arrange the tomato and egg wedges over the potatoes.
Scatter the finely chopped cucumber, finely chopped scallions, finely chopped green bell pepper, and black olives over the top.
Pour the remaining vinaigrette over the salad and toss gently to combine.