Clean the potatoes and add them to a large pan of boiling water.
Cook for about 20 minutes or until the potatoes are fork-tender.
In a large mixing bowl, stir together the mayonnaise, onion, mustard, olive oil, garlic, lemon juice, dill, salt, and pepper.
Slice the cooked potatoes into ½ or ¼ depending on their size.
Combine the chopped potatoes with the sauce in the mixing bowl and stir to coat the potatoes.
Leave the salad to cool at room temperature, then store covered in the fridge.
