Place the potato matchsticks into a large pan of cold water for 30 mins to remove excess starch. Drain the potatoes and spin in a salad spinner to remove all excess water.
Fill a deep-fryer one third full with oil and preheat to 180C.
Heat a large, heavy-based pan (with a lid) until very hot. Pour in the extra virgin olive oil, then add the butter, spring onions, shallot, garlic, chilli and thyme. Cook for about 1½ minutes, shaking the pan until the vegetables start to wilt.
Add the mussels and shake the pan so they form an even layer. Cover with a lid and cook for another 1-2 minutes, shaking the pan a couple more times.
Remove the lid and add the wine and Pernod. Toss together and cook for another 1½ minutes until the wine is reduced by half. Replace the lid and cook for a further 1 minute. Place a large colander over a bowl and tip in the mussels. Discard any mussels that remain closed.
Fry the chips in a chip basket, a couple of handfuls at a time, for about 2 minutes, until they are a crisp and golden brown. Tip onto a tray lined with kitchen paper to drain, then transfer to a serving bowl and sprinkle with salt, pepper and cayenne. Toss well.
Meanwhile, pour the strained mussel liquid back in the pan, reheat and stir in the crème fraîche and parsley. Taste and adjust for seasoning. Return the mussels to the pan and reheat, shaking the pan, then divide between two large bowls.
Serve with a glass of Wolf Blass Gold Label Riesling and the bowl of chips alongside to dip in the juices.