Mussels in Creamy Wine Sauce with Chips

Potatoes: any floury variety that roasts rather than waterlogs — the kind sold loose for baking, not the waxy salad ones that stay bullet-hard and refuse to crisp. Cut them to chip size, toss in oil thinly enough that it coats rather than pools, because a chip sitting in its own puddle of oil in a tray steams instead of browning, and a steamed chip is a sad, pale chip. Turning them partway through is what stops the underside going soft while the top crisps — contact with hot metal is what browns, so every side needs its turn down.

Mussels: 2kg sounds like a lot until you remember maybe a fifth of the weight is shell and water you'll throw away, and that a mussel that doesn't open is a mussel you never ate anyway, so buy generously. Farmed rope-grown mussels, which is most of what you'll find in a UK supermarket, are already fairly clean — the old instruction to soak them for hours in water with oatmeal or flour, to get them to "spit out grit," is largely a leftover from wild-harvested mussels dragged off a rocky shore. Scrub, don't soak — soaking in fresh water stresses them and can kill a few before they even reach the pot, which just adds to your discard pile for no gain.

Onion, chilli, garlic: this trio isn't flavour decoration, it's the base the wine reduces onto. Softening them in oil first — not colouring them — means they melt into the sauce rather than crunching through it; a browned onion here would taste of caramel and fight the delicate mussel liquor instead of supporting it. Any onion variety works; the chilli's job is a background warmth, not heat you're meant to notice, so use less if your chilli runs hot and more if it's mild — taste is the only honest guide, the "half a chilli" on the list is somebody else's chilli, not yours.

Wine: a dry white, something you'd be happy drinking, because the alcohol cooks off but the flavour doesn't — a wine that tastes thin or sour on its own will taste thin or sour concentrated into 100ml of sauce. This is also the whole reason the dish exists in this form: mussels and white wine is a coastal, French-leaning pairing because wine was the acid and the flavour people on those coasts already had in the house, cheaper and more available than lemons ever were. Moules marinière is this recipe's parent; the cream and the chips are what turn a bistro starter into a full plate.

Straining the mussels out before reducing is the step people skip, and it's the step that saves the dish. Leave the mussels in the pot while the sauce boils down and they go from tender to rubbery — all that extra heat has nowhere useful to go once the meat's already cooked, it just toughens it. Pulling them out, covering them with a plate or a tent of foil to hold their heat, lets the sauce reduce hard and fast without cooking the shellfish a second time. Reducing to roughly 100ml isn't an arbitrary number — it's the point where the liquid's gone from thin wine-and-juice to something with enough body to actually coat, concentrated salt and all, which is also why you season after reducing, not before, or you'll oversalt it.

Cream: double cream, because it has enough fat to sit in a hot, slightly acidic, slightly salty liquid without splitting into watery curds — a single or half-fat cream is more likely to break the moment it hits that reduced wine. If you're avoiding dairy, crème fraîche behaves similarly for the same fat-content reason, though it'll bring its own tang; a dairy-free cream alternative with enough fat content can work but check it's one meant for cooking, not for tea. Lower the heat before it goes in — this isn't about tenderness, it's that a vigorous boil can still split even a good cream once the acid and salt are both already in there.

Parsley at the end is cheap, obvious, and still worth saying: it's raw, bright, slightly bitter against all that richness, and it only works added at the very last second, off the heat — cooked parsley just goes dark and loses the thing it was there for.