Note: For the 32 days between February 1st and March 4th, I'm adopting a completely vegan lifestyle. Every weekday I'll be updating my progress with a diary entry and a recipe. For past posts, check here!
The other day I was seriously strapped for time when it came to lunch. My dog Hambone had taken longer than expected to use the outdoor facilities (it's always longer than expected), I had a few dozen emails and Twitter queries that needed de-querifying, that episode of Breaking Bad was just a bit too interesting to stop watching after the 20 minutes I'd committed to watching it, and the apartment was just a touch too cold to get out of the shower right after rinsing. My wife was on her way to a meeting, and the window of opportunity before she resigned herself to going hungry for a few more hours until she got back was rapidly closing.
I needed lunch, and I needed it STAT.
My usual omnivorous go-to in those situations? Easy. Some simple cooked pasta with whatever vegetables we happen to have in the fridge, along with an easy emulsified butter sauce. The technique couldn't be simpler: blanch the vegetables, cook the pasta in the same pot, drain it, reserving some liquid, then mix it all back together, adding a knob of butter and a few big twists of black pepper. The magic happens when the butter emulsifies with the starch-laden cooking liquid and forms a sauce that clings to the pasta, delivering peppery bite and slick texture to each and every piece.
Now, I do like my butter as much as the next guy, but in all honesty, I'd pick olive oil over butter any day in terms of sheer flavor. Good olive oil, that is. Luckily, I happen to be somewhat of a collector and obsessive when it comes to good olive oil, so there's never any shortage in the López-Alt household.
But the problem with olive oil is that it simply does not have the same emulsive properties as butter does. That is, when I try to follow the exact same procedure for my quick veg-and-pasta dishes replacing the butter with olive oil, here's what happens:
Rather than emulsifying into a smooth, clingy sauce, I end up with a watery sauce covered in oil slicks.
So what? you might say. Isn't the flavor all the same anyway?
Well, sort of. The flavor might all be there, but the real problem is that when your oil and water are separate like that, they tend to run off the pasta and collect at the bottom of the bowl. You end up with dry, bland pasta and vegetables on top, and a wet, soupy mess left when you're finished with it. Indeed, it's exactly the same as the importance of a good, emulsified vinaigrette when you're making a salad. Without one, you end up with underseasoned greens and broken oil and vinegar at the bottom of the salad bowl.
Butter has natural properties that allow it to emulsify quite well with water-based sauces like this one, especially with the help of a bit of starch from the pasta cooking water.
Olive oil, on the other hand, is much harder to mix into a smooth, slick sauce.
The solution proved to be quite simple. I know that starch helps emulsify sauces by physically impeding fat molecules from coalescing in a fat and water mix. That's the whole reason you use pasta cooking water to thin your sauces (and the reason why restaurant pasta gets better and better over the course of a service as the pasta water gets starchier and starchier). The extra starch helps emulsify the sauce, making it stick to your pasta better
It only takes a bit of starch to emulsify a butter sauce, but it takes a bit more effort to properly emulsify an olive oil-based sauce. So why not just add that extra starch?
That's precisely what I did. By adding a half teaspoon of cornstarch for each two servings of pasta, I was able to create a sauce that clung to the pasta as well as any butter-based sauce, but had all the bright, vibrant, complex flavor of olive oil. Best of both worlds!
Staying in tune with my plenty-of-veg ideals, I like to go extra heavy on the veg and extra light on the pasta reversing the ratios of a more traditional pasta and veg meal.
Of course, by the time I was finished explaining all of this to Hambone in my typical professorial tone, my wife was long gone, leaving me to lick the bowls myself and wondering what sort of trouble I'd find myself in when she got back.
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About the author: J. Kenji Lopez-Alt is the Chief Creative Officer of Serious Eats where he likes to explore the science of home cooking in his weekly column The Food Lab. You can follow him at @thefoodlab on Twitter, or at The Food Lab on Facebook.