Wash potatoes and boil for about 45 minutes, until pierced easily with a fork.
Once potatoes are boiled run through cold water and peel.
Cut potatoes in your preferred shape and place in a bowl.
Mix the olive oil with the lemon juice (or vinegar) and add to the potatoes (make sure the potatoes are warm so that they will absorb the olive oil well, this makes a good salad) and mix gently.
Add the onion and oregano (rubbing it between your fingers to release the aroma) and blend.