-
1
Place the cockles in a large bowl and cover with cold salted water. Hold for 30–60 minutes so the cockles expel any grit. Drain and rinse. Discard any shells that are broken or that remain open and do not close when tapped.
-
2
Set a wide, heavy pan over very high heat. Add no more than 3–4 tablespoons of white wine or water to the pan — enough to create the first burst of steam and nothing more. Arrange the cockles in a single layer, cover tightly, and do not lift the lid. The liquid must reach a hard, rolling steam immediately; if the pan is slow to respond, the cockles will stew rather than flash open.
-
3
Steam for 2–3 minutes. This is where the dish lives or dies: lift the lid the moment all shells have opened — approximately 2 minutes over high heat — and remove the pan from the heat immediately. Any cockle held over heat beyond the point of opening will turn rubbery within 30 seconds. Discard any shells that have not opened.
-
4
Transfer the cockles to warmed shallow bowls. Pour every drop of the cooking liquid from the pan over the shells — it is the concentrated brine and flavour of the dish. Serve at once with lemon wedges on the side. No sauce, no garnish beyond the lemon.