Preheat oven at 180° C.
1. Wrap potatoes and onions together in aluminum foil and close tightly.
2. Bake in oven until soft for approximately 45 minutes depending on size.
3. Allow them to cool.
4. Peel potatoes and onions and cut them in cubes.
5. Serve in large open serving bowl. Season and add olives.
6. Drizzle with olive oil and lemon (or vinegar if preferred). Serve hot.