Boil whole potatoes with their skins on until tender when pierced with a fork.
In a separate pot, boil the eggs for 10 minutes until hard-cooked.
Once cooled, peel the potatoes and cut them into bite-sized pieces, placing them in a large mixing bowl.
Finely chop the onion and add to the bowl with the potatoes.
Gently fold in bite-sized pieces of fish and chopped hard-boiled eggs.
Add the olives and combine everything carefully to avoid breaking the potatoes and eggs.
In a jar, make the dressing by combining olive oil, vinegar, salt, and pepper. Shake well to mix.
Pour the dressing over the salad and gently toss until evenly coated.
Refrigerate for at least one hour to allow the flavours to develop.
Before serving, sprinkle with fresh parsley and serve cold.