SHE. – What are the differences between flat oysters and cupped oysters?
Hugo Boutrais. – The flat oyster is an endemic French oyster with the characteristic of being flatter while being rounder in terms of shape. In France, it is associated with the Latin name Ostrea edulis. This oyster became rare in the 1960s, following significant mortality due to a disease specific to oysters. It is still produced and raised in France, but in smaller quantities. 95% of oysters farmed and sold in France are cupped oysters. The shape, more elongated, is hollow below and the shell above is flat. The Pacific oyster belongs to the species Magallana gigas, which was previously called Crassostrea gigas. It was introduced in 1960 and imported from Japan, following the problem of flat oysters. Between Japan and France, there are a lot of climatic similarities, so this oyster does very well in France.
For its taste, the flavor of the flat oyster is quite delicate, with a tangy side, sometimes even a little rocky. There is a very iodized side for the fine cupped oysters, and a sweeter and nuttier side for the special ones.
The flat oyster requires a slightly different opening method. We open it by the hinge, by the bottom, when we open the cupped oyster on the side.
SHE. – What is your advice for opening an oyster without getting hurt?
HB – It takes a little help to learn, with some fundamentals. First of all, you have to hold your knife well: let very little of the blade protrude from your holding the knife. People tend to grab the knife by the handle and try to open their oyster using pressure. That’s when you get hurt, when you slip. What you should avoid at all costs is keeping the blade at bay. On the contrary, you must take the blade in your hand and hold it well, with only one centimeter of the blade protruding from your holding. Obviously, you can use a protective glove. There are mesh gloves, which are effective. Otherwise, you can use a thick cloth to protect the hand holding the oyster. Beginners injure the hand holding the oyster. Afterwards, when you become an expert, you injure your other hand. It’s the other hand that slips on the oyster. To open, you must insert the knife two-thirds of the way. We have the “butt” of the oyster towards us and we identify the place where there is the muscle which holds the two shells. To identify it, it is at the level of two thirds of the length of the shell. Generally, this is where we try to insert the knife between the two valves. We scrape to cut this muscle which forms the joint of the oyster. What is also essential is to check that there are no shell fragments in the oyster. Very important, there is a part of the oyster which often remains stuck to the upper part, which is flat. The best thing is that this veil remains “in solidarity” with the whole shell. This is what allows us to preserve the shell and present it in the best possible way.
SHE. – Should we throw away the first water?
HB – The first water is always quite salty and loaded with minerals. It is not very tasty, I recommend throwing it away. The oyster can replenish its water up to seven times and the second water will already be tastier.
SHE. – What is this water for?
HB – An oyster filters water, naturally. She lives in this sea water and always has this water reserve, her reserve of life. As long as it is full of water, we will say that it is alive. If it ever loses this water, it dries up and, little by little, dies. I like to say that the oyster has 7 lives like a cat which rests on the 7 waters that it can remake (on average).
SHE. – How do you know if an oyster is fresh?
HB – When you open it, an oyster is quite heavy. We feel the weight of its water. It is not trivial or negligible. A very fresh oyster is an oyster that will have lost its water without replenishing it. If it is closed, it sounds hollow. When we pack the oysters, we tap them together. We listen. If the noise is hollow, it means the oyster is dry. She is not necessarily dead, but has lost a lot of water. You can check this by touching it. We open it then touch the gills a little. If it shrinks, she’s still alive. It is a shellfish that is eaten alive. If it still moves, we can still eat it. The first thing to check is the presence of water. If it’s already open, that also means it’s dead. If it’s too easy to open, it’s not good. It doesn’t smell good, in the first and figurative sense of the word. A fresh oyster smells like oysters. An oyster that is not fresh smells very bad, there is no doubt about it. When we don’t know this smell, it’s really the smell we can smell when we leave fish offal in our trash.
If it is already open, if it yawns, you must try to close it to see if it holds. If we see that it maintains its closure, that means that it still has strength and is edible.
SHE. – How to ensure that oysters remain fresh after purchase?
HB – The ideal temperature is between 4 and 10°C. The bottom of the fridge, where you store the vegetables, is ideal. We don’t always have a choice, but the best is to avoid dry places. It’s better to be damp and cold. How to reproduce humid cold rather than dry cold? The fridge is dry cold. To have a humid cold, we keep the oysters flat, with the hollow side down, because they need to retain their water. When it gets tired, the oyster opens a little, and if it is crooked, the water flows out. Whereas if she is tired, but she is upright, the water stays inside and she survives more easily. Optionally, you can cover the oysters with a damp cloth, to avoid this excessive exchange between the dry side of the fridge and the wet side of the shell, this avoids thermal shock and drying out. Shelf life is on average 7 to 10 days. In reality, there aren’t really any days you can keep them, eat them, as long as they’re alive.
SHE. – Is there an obligation to buy these oysters at the last minute?
HB – No, on the contrary, we can do it in advance. 5-6 days in advance is very good, even 10 days in advance for specials. On fine, classic oysters, it’s a little riskier, because they are fragile. That’s why they’re cheaper, by the way. But I would say 5 days in advance.
SHE. – At what temperature should you serve oysters?
HB – If you store in the cold, it is good to let them come to room temperature for 1 or 2 hours so that they warm up again. If an oyster is served at 10-12°C, this is not a problem. On the contrary. It will be tastier, when you eat it cold it tends to taste a little salty. The cold amplifies the sensation of salt.
