To make the marinated potatoes: Wash the potatoes & put in a pan of cold salted water. Bring to the boil & cook til tender. Meanwhile, combine the oil, vinegar, mirin, chilli, garlic, lemon juice/zest & dill in a container large enough to hold the potatoes. Once the potatoes are cooked, strain them & while still hot, put in the container. Ensure the marinade covers all the potatoes. If it doesn't, add equal parts white wine vinegar & extra virgin olive oil. Leave to cool, cover & refrigerate until needed.