Put the potatoes in a pan and cover with cold, salted water. Bring to the boil, then bubble for 15-20 minutes until cooked through.
Preheat the oven to 200ºC, gas mark 6.
Drain the potatoes and set aside to cool slightly.
In a large bowl, mix the remaining ingredients.
Add the potatoes and toss well until coated; season.
Tip the potatoes onto a large, lipped baking tray, reserving any leftover marinade in the bowl.
Use a potato masher to gently smash the potatoes, just enough to fatten them without breaking apart.
Roast for 40-45 minutes until golden and crisp.
Drizzle over the leftover marinade and serve straightaway.
