Boil the potatoes until tender, drain and set aside to cool.
Dry potatoes well, gently smash the cooked potatoes using the palm of your hand. Coat with olive oil and season with salt and pepper.
Preheat a grill pan. Place potatoes on pan and allow to crisp (about 2 minutes per side). Avoid turning to allow for dark grill marks.
Mix lemon juice, zest, olive oil and parsley together, pour generously over the crispy grilled potatoes.