Moules-Frites (Mussels and Chips)

Variations

• Marinière: what the recipe above is. White wine, shallots and parsley, nothing else, and the first line on every Belgian brasserie's list.
• À la crème: lift the mussels out, then reduce 100ml of cream into the remaining broth. Softer, at the cost of covering some of the sea flavour (dairy and heat).
• À la bière: Belgian wheat beer instead of the wine — the country's other export doing the same job, which is exactly the logic carbonnade flamande is built on (cooking with alcohol).
• Provençale: plenty of tomato and garlic, in the southern French manner. Go far enough down that road and you are heading towards bouillabaisse.
• The frying fat: beef dripping is the Belgian original — a higher smoke point than vegetable oil, and a savoury smell of its own. It stops being vegetarian, and it sets solid white in the pan, which is a nuisance (choosing oils).
• The sauce: mayonnaise is the default, with andalouse (mayonnaise, tomato and pepper), tartare and samouraï (mayonnaise and harissa) close behind. Ketchup is regarded in Belgium as something for children.
• Season: the Belgian rule is months with an R in them — September to April — which lines up with mussels being plump again after spawning.
• How it differs from clam chowder and paella: in both of those the shellfish is one ingredient among many and the liquid is made separately. Here the shellfish brings the broth, which is why the only liquid added is one glass of wine.
• Against fish and chips: two countries that both made fried potato a national food, differently. The Belgian cut is thicker, fried twice, and dipped in mayonnaise rather than doused in vinegar.

Tips

• Do not add water. This is the common mistake. Two kilos of mussels release cups of seawater as they open; anything you add only dilutes it, and a deep pool in the base means the bottom layer boils rather than steams. 150ml of wine is the ceiling.
• Four to five minutes, and do not wait for the last one. The window is narrow — two minutes past open and the meat has shrunk by half and gone rubbery. Do not sacrifice the majority to the stragglers.
• Sort them while cleaning. A gaping mussel that will not close when tapped is dead, and so is a cracked one. Conversely, ones still shut after cooking may just have a stubborn muscle, but there is no way to tell, so throw them out.
• Debeard just before cooking. Pulling the beard starts the mussel dying, so do it when you can go straight to the pot. Pull it towards the wide end of the shell, not the point.
• Big pot; toss it, do not stir it. More than half full and steam cannot circulate, so only the bottom cooks. A spoon chips the shells and puts fragments in the broth (steaming).
• A kilo per person. Most of that weight is shell — the actual meat is 200-250g. First-timers almost always buy too few.
• Fry the potatoes twice. 150°C cooks the inside, then, after they cool, 190°C sets the outside. In one pass the outside burns before the middle is done. The cooling in between is the point — that is when steam leaves the interior, which is what lets the second fry crisp (deep frying).
• Dry the potatoes completely. Wet ones spit instead of frying and come out soggy. Rinse, then press them dry in a cloth.
• Salt them the second they leave the oil. Salt only sticks while the surface fat is hot; sprinkle it over a plated pile and it falls straight through (salt and seasoning).
• Leave the last spoonful of broth in the pot. Grit from the mussels settles there. Ladle the broth out rather than pouring it.
• Pick leftovers out of the shells. Reheated in the shell they toughen; picked and stirred into pasta or fried rice at the last moment they are fine (reviving leftovers).