04/23/2014 09:31 am ET Updated Jun 23, 2014

Cooking Off the Cuff: Got Fish? Got Roasted Vegetables? Get This Olive Sauce

For weeks I've been whining about how there's no spring produce in our New York farmers' markets even though it's nearly the end of April (and I found the other day that even last season's carrots were disappearing from the stands). Well, I looked at my Cooking Off the Cuff archives for April 2012 and 2013 and found that the situation was the same then. It's just that when Jackie and I were in the UK and France last month things were much further advanced and we contracted a case of asparagus-envy. So maybe I'll shut up about that, at least for now.

This doesn't alter the fact that we're still eating as though it were January, except with the windows open wider, so here's a pretty much season-neutral sauce that I've served with fish and with slow-roasted vegetables: An olive/olive-oil butter sauce, made like a beurre blanc, but so deep-hued that it can hardly be called "blanc."

The notion of chopped olives in a warm emulsion, though not revolutionary, comes from a meal we had last autumn in Amsterdam, at the good restaurant Marius. As I said at the time, I was intrigued by the delicious, rather liquid, olive "mayonnaise" served with one of their fish dishes. It had the consistency of a beurre blanc, but was very different in flavor. As I recall, however, it did indeed taste of shallots and had a light acidity that could have come from wine or vinegar. And it was packed with chopped olives.

I could easily be misremembering that: It might have just been a loose mayonnaise with olives added. But what I've been thinking of since then was using olives and olive oil in a more typical beurre blanc, and that's what I did. Twice, in fact.

For four servings, I sweated a large shallot, finely chopped, in butter with a little salt and pepper and some fresh thyme leaves. While it was cooking, I roughly chopped enough olives to make about 2/3 cup loosely packed (I used black ones the first time and a mixture the second, but use whichever ones you like so long as they're not bland). As I was doing this I stirred the shallots occasionally and made sure they weren't starting to brown - though that wouldn't matter as much here as it would in a classic beurre blanc, where most cooks wouldn't sweat them in butter at all. When the shallots were completely soft (taste some), I added the olives to the pan, warmed them through and set the mixture aside until dinner time.

When the ingredient that was to be sauced (fish once, "forgotten" celery root the next time) was just about ready, I put the shallot-olive mixture back onto medium-high heat and when it started to make sizzling noises stirred in 1/3 cup dry white wine. When this had reduced to something more than a tablespoon, I lowered the heat a notch and vigorously stirred in about 2-1/2 ounces (say, 70 g) of butter, swirling the pan as I did so. This formed a nice creamy emulsion. Off the heat, I added a bit less than two tablespoons of lemon juice, some grated lemon zest, about a tablespoon of flavorful olive oil and another few thyme leaves -- these final additions freshened the flavors already in the sauce. A check for salt, and the sauce was done. I took care not to keep it over heat -- it might have separated and it wasn't worth taking that chance.

The time I served it with fish, it was with roasted cod and sweet onions from Georgia (the U.S. state, not the country in the Eurasian Caucasus). Then a few days later I served a first course of forgotten celery root with this sauce. It offered strong flavors, but with a soft underbelly of butter and sweet shallot, and it was just about perfect with the fish and a seven-out-of-ten match with the celery root. Worth keeping in the repertoire, no matter what is or isn't in the farmers' market.

Got Fish? Get This Olive Sauce