An oyster primer from America's Test Kitchen

Oysters are both intriguing and intimidating to many people; they just aren't sure quite how to approach them. But, learning how to buy and prepare them can lead to very delicious results. Dan Souza is editor-in-chief of Cook's Illustrated for America's Test Kitchen. Managing Producer Sally Swift talked with him and got his expert advice for selecting, opening, cooking and eating oysters. America's Test Kitchen also share with us their versatile recipe Grilled Clams, Mussels or Oysters with Spicy Lemon Butter.

Listen to more stories about the wonders and history of oysters from our all-oyster episode, The Oyster King and the Seagull Test.

Sally Swift: I want to start with the big question: True or false – should we only eat oysters in the months that contain the letter “R” in the name?

Dan Souza: This used to be true, and it’s technically still true today if you’re eating wild oysters. Wild oysters were the norm back in the last century, but nowadays people pretty much eat exclusively cultivated oysters. The reason for this rule was because the months without an R, such as May, June, July and August - essentially, the summer months - were spawning season for oysters, and oysters that are spawning don’t have a very good texture. It wasn’t about it not being safe to eat oysters in the summer, it was simply that they don’t have the best texture. Nowadays, because we’re eating farmed oysters, you can enjoy them throughout the year.

SS: And we are mostly eating farmed oysters, correct?

DS: That’s correct. By and large, you’re eating farmed oysters. There are still a few areas where there are wild harvested oysters, in Europe particularly, but most oysters are all farmed.

Dan Souza Photo: America's Test Kitchen

SS: What do we need to look for when buying them?

DS: The key is for oysters to be alive and well when you buy them. This is not true for all foods that we eat but it is true for shellfish and oysters – it’s really important. Think of them as produce. You wouldn’t want to buy from a place that leaves them lying around for weeks; you want to buy from a place that goes through a lot of oysters. You also want to make sure that the lid on the oyster is tightly closed at all times. That means that it has plenty of moisture inside and all that nice liquor in there. It also means that it is alive. This is important to look for. A good fishmonger will do this trick: gently knock them together and listen to the sound that they make. If an oyster is packed with liquor and tightly closed, it’s going to make a deep thud. If it sounds hollow, that means a lot of the liquor has drained out, and that oyster is either dead or at least not very healthy. If you see your fishmonger doing this, then that’s great. They should self-select the ones that are good.

SS: I have never seen a fishmonger do that, I must admit.

DS: The good places will. They know that trick. And the final point to buying good oysters is to consider their size. You can eat an oyster that is very small or one that is really big and they’re all delicious. They never really get tough even as they get quite large. But you do have some challenges. A very large oyster is going to be pretty tough to open, and it might be a little too much for whoever is eating it to slurp down in one gulp. And on the other hand, if it’s too small, you will be opening more oysters to feed people. You know, it’s a hard task to open them – and it could be more difficult to get your oyster knife in there. Look for average-sized oysters with a nice deep cup and a fishmonger who sells a lot of them and knows that nice knocking trick.

SS: What’s the best way to store them when we get them home?

DS: For storage, just like with all seafood - and especially live seafood - cold is your friend. You want to get them as cold as possible without them freezing. The real key to that is using ice. The best method is to put the oysters in a colander, cover them with ice, and put that colander in another bowl. It allows you to have the oysters touching ice, and then as the ice melts the water drains away. You don’t want to do what I did when I worked at a very fancy French seafood restaurant. I forgot to take the oysters out of the ice and let them sit overnight in it, and as that ice melted, they were surrounded by fresh water and died. Oysters love saltwater, they die in freshwater. You always want to have a place for that melted freshwater to drain away.

SS: I had no idea. And you know, that crushed ice that restaurants serve oysters in is there for a reason. The oysters taste much better when they’re raw and they are cold.

DS: Exactly. We love oysters nice and cold, and crushed ice is perfect for a few reasons. When you get served oysters at the table coming on something like salt or a bed of greens or something like that, then that is the coldest they will ever be. So, you feel this certain rush to eat them while they are nice and chilled. If they show up on a bed of crushed ice, it means that you have plenty of time to hang out with them. They’re just going to get colder and they’re going to stay for a long time. You can have sips of wine and oysters and have a good time with the people you’re dining with and not worry that the oysters are not going to be as good as they sit.

SS: That is the way to go. I want to get to cooking in a minute, but I need to know if you are a sauce-on or a sauce-off person with your raw oysters? I find this divides oyster eaters.

DS: My guess is that it probably divides oyster eaters over their lifetime. I know for myself, I used to use a lot more sauces than I do now. When I first started eating oysters, I liked cocktail sauce, I liked mignonette, even hot sauce. I was getting used to the taste, texture and nuance of the oyster. As time went on, I switched over to just using lemon. My preferred way now is with no sauce at all, but with a nice steely, bright white wine as an acidic component. So, sipping on that and eating the oysters. But there is no shame in using sauces. I think you taste it the most when there’s nothing else.

When grilling oysters, be sure not overcook them. Once the oyster shell opens, Dan Souza says they are ready to come off the grill. Photos: America's Test Kitchen

SS: Let’s get into cooking them. What are your favorite ways of dealing with oysters and heat?

DS: There are a ton of different ways to cook oysters. Something important to keep in mind is that oysters are pretty mild. If you’re going to take them out and batter them and fry them and put them in a flavorful dipping sauce, you’re going to lose a lot of that oyster flavor. For me, the only way I really like to cook oysters is on the grill. If you have a lot of people coming over and you don’t want to spend the time shucking oysters, it couldn’t be any simpler.

You start with a medium-hot grill. Scrub the oysters well, then put them on the hot grill cup side up. Put a lid on it and let it go for a couple of minutes. All you’re looking for is that shell to pop open just a little bit; it’s not going to pop open wide. Once that happens, take them off the grill. And I like to have a landing zone. I take a big sheet of aluminum foil, crumpled it up a little bit, and basically make a nest out of foil where they can come off the grill and sit right on that. The foil keeps them upright so that you don’t lose any of that nice liquor.

Once they’re over there, you want to get any knife, and this can be a paring knife, a butter knife, or if you have an oyster knife, that’s great. You’re going to slide in that big opening that you now have access to and sever the adductor muscle on top. Take the top shell off. Slide the knife underneath and sever the adductor muscle on the bottom. Then they’re ready to go. You can serve them with lemon wedges, or flavored butters – it’s really the easiest possible way to serve oysters, and because you’re not doing a lot to them, they’re enhanced by the grill but not overpowered by any flavors.

SS: And are they cooked or are they just warmed up?

DS: For the most part, if you keep going you can overcook them. I like them gently warmed. You see that they’ll tighten up a little bit, firm up a bit with the heat, and you can keep going longer if you wanted to, but I think you get the nicest experience if they’re just warmed up, with a little bit of grill flavor, and easier to open.

SS: What do you do with the tubs of shucked oysters afterwards? Do you ever take them on?

DS: If they’re coming from a good fishmonger and they’re fresh, then those are great to use for making an oyster stew, which is a nice classic dish. Or if you wanted to do a deep-fried oyster, those are the ones that I would go for. It’s going to be a ton of work otherwise, and you’re not going to notice the differences in how they were shucked once they’re battered and fried.

SS: That makes sense. I have one last question about eating oysters. We’re seeing a lot of dollar oyster places these days for happy hour. Is that a good thing or a bad thing? I am afraid to ask.

DS: If I only had one answer for this, my answer would be, "no, it’s not a good idea." But it’s a little more nuanced than that. You have to look at the place that is selling the oysters. If it is a restaurant that serves a lot of seafood, that often serves oysters at full price and is offering a discounted price on them, then that’s probably a good bet and I would check them out. If on the other hand, it’s a bar or restaurant that really doesn’t focus on seafood, one that doesn’t serve oysters often and is just trying to just get people in the door, I would be wearier of going to that establishment.

It really comes down to best practices, the stuff that we talked about: storing them really cold, knowing how to properly open an oyster, that’s all going to come with working with oysters a lot. If you go in a place and order, the sure sign that you don’t want to be eating those oysters is that they look like they were opened by seagulls. By that I mean the way seagulls open oysters.

SS: Massacred.

DS: They pick them up, fly high in the air and drop them on rocks. So, they’re open but there are shards of shell everywhere, there’s dirt in them, and obviously the adductor muscle wasn’t cut well. You can look at them and tell pretty quickly if they were handled with care. Not served on ice.

SS: OK, it’s the seagull test.

DS: The seagull test. That’s your final guide.