Is saba normally cured/marinated at a sushi bar?
I ate dinner at a mediocre sushi restaurant recently and ordered saba. It came to the table marinated and clearly was not raw. I asked about it because I have only ever received mackerel completely raw at other sushi bars. They were really indignant about it and told me all sushi restaurants serve it marinated (I'm guessing they meant in vinegar which cooks it by acidity). I insisted they I had been served completely raw mackerel before (at much better sushi bars, but I didn't say that). Am I wrong? Was the sushi I had eaten previously marinated without my knowledge? (I'm thinking there's no way I can't tell the difference between marinated and raw fish, I've eaten a lot of sushi before).
I have seen mackerel fillets in sushi bars side by side with yellowtail and the usual suspects, but along the way the standard mackerel serving has been marinaded in rice wine to cut the oily, fishy characteristic (which is pretty strong- it's not my favorite). I don't know for how long...anyone?
To the best of my knowledge, saba is always cured/marinated in some way. We've even bought it at a Japanese market and it's lightly cured. Spanish mackerel, OTOH is raw - usually filleted just before serving.
I hate to tell you but you can't tell the difference between marinated/cured saba and a fresh raw fish. It's always cured for sushi.
Saba (mackerel) is almost always cured/marinated in some form. But the amount of curing varies from cook to cook, from regional styles, and from the type of saba used. There are several types of saba, the better ones being caught around Japan. So it might depend on whether you had a Japanese species of saba (like gomasaba, hirasaba, honsaba, masaba, sekisaba, etc.), which wouldn't need to be cured for very long (seeming more raw than cooked in acid), and you may have had American/Pacific saba that probably requires a little more curing. It may also depend on the season you ate the saba, as Japanese saba is tastiest in the Fall/Winter.
Here's an interesting article that mentions how raw saba is looked upon in Japan, and a company that's marketing it.
I'm sure that procuring good saba for sashimi is difficult in the US, unless it's coming directly from Japan, but since it's a fish that spoils quickly, it needs to be frozen and also treated with care. It makes sense that most of the itamae that spots my love for saba, will usually either be very excited about their saba from Japan, or they tell me that they only have American saba, so I should get something else.
It's highly unlikely you've had raw saba. I'm guessing what happened is that in your recent experience, the 'mediocre' place had a stronger pickling solution than what you're used to getting. Most sushi restaurants guard their recipes (and for those that grew up eating it, nobody's recipe stacks up to Mom's/Obachan's), so there is room for a lot of differentiation in taste.