Put the potatoes into a pan of salted water and bring to the boil. Simmer for about 15 minutes until they are just cooked, without being soft and breaking up. Drain in a colander.
Tip onto a lightly oiled roasting tray and used a potato masher to squash each potato flat. Brush with olive oil and scatter with the sea salt, pepper, seeds and herbs.
Put on the top shelf of the oven for 20-25 minutes until crisp and golden, then serve straight away.