The oyster is a sustainable hero that can filter 100-200 litres of water a day, and in doing so helps purify entire estuaries. But that doesn’t mean it’s in any way “dirty”. Farmed oysters are regulated and grown in clean water systems, so there’s no need to worry about their purity; in fact, much like fine wine, they take on the characteristics of their terroir, and grow rich in nutrients, including vitamin B12, magnesium and zinc.
Like mussels and clams, oysters are sold alive, which is why many people, having bought them for a special meal, worry about keeping them for more than a day or so afterwards. Stored properly, however, they can keep for up to 10 days. To prevent wastage, lay them flat side up and tightly packed in an open container, cover with a damp cloth, so they can breathe, and put in a fridge set below 5C. Before eating, shuck and check they are alive, full of liquor and smell fresh.
An oyster is remarkable enough as it is, but it’s fun to experiment with pairings such as this punchy ceviche.
Rhubarb oyster ceviche
I discovered ceviche on my travels in Latin America, where it’s served in fish markets as a refreshing snack made with all sorts of fresh seafood such as conch, bass and marlin. The sustainability of much fish is dubious, however, so it’s wise to approach eating it with caution. Oysters, though, are a great sustainable choice, and they are even thought of as a regenerative fish species. (With other fish species, look for the MSC, or Marine Stewardship Council, certification or check the Marine Conservation Society’s Good Fish Guide.)
It is thought that ceviche originated in Peru as a way of preserving fish. In Peru, they call the marinade leche de tigre, or tiger’s milk, and it’s even drunk as a shot with pisco, a Peruvian brandy. The tiger’s milk from this oyster ceviche is the best I’ve ever tasted, and makes the most amazing cocktail – just mix 25ml chilled oyster ceviche juice with 25ml pisco (or vodka) and serve.
100g rhubarb, 80g roughly chopped, the rest very finely diced
1 tsp unrefined sugar
12 rock oysters, freshly shucked
3 coriander stalks, crushed
2 tbsp lime juice
Put the chopped rhubarb in a saucepan with two tablespoons of water and a teaspoon of sugar. Bring to a boil, cover and simmer for five minutes, then strain into a bowl to collect the juices and leave to cool before refrigerating. (Save the pulp for your breakfast cereal or yoghurt, or really push the boat out and use it to make a granita to serve alongside the oysters.)
Shuck the oysters and marinade them for 30 minutes in the cooled rhubarb juice, the crushed coriander stalks and lime juice. Serve the oysters in the half-shell doused in a little of the marinade and decorated with the diced rhubarb.