Introduction
I used to believe that, for the best results, you needed to cook dry pasta in water that’s at a rolling boil. On top of that, you needed four or five quarts of water to have enough thermal energy in the water so it could rebound to that rolling boil quickly after the pasta is added to the water. It seems Kenji Lopez-Alt had similar beliefs until he saw his wife successfully cook pasta in a tiny pot with barely enough water to cover the pasta, with the water heated to just a simmer. I love what Kenji does when confronted with unknowns in the kitchen. He digs into the science of cooking and runs a rigorous series of tests to figure it out.
This post will only summarize the key results and present the new cooking method. Kenji has a very entertaining write-up of the science posted here. He quantifies the technique in this recipe. I encourage you to check out both of those links.
Why Do We Need a New Way to Cook Pasta?
While the traditional way of cooking pasta in a large volume of well salted water wasn’t difficult, this new method is just simpler. It feels that way to me, anyway, and I’m not exactly sure why. I used to eyeball both the large volume of water and the amount of salt that I added to that water. This new technique requires measurement, which seems to be more bothersome. But, somehow, I’m comforted by the certainty that comes from measuring out 2 quarts of water and one tablespoon of salt.
The biggest advantage is the extra starchy pasta water that it produces. Many pasta recipes call on the use of some pasta water to finish the sauce. Restaurants often make great use of this technique. They use the same water throughout the night to cook their pasta. This water becomes very starchy as the night progresses. The starch is why the pasta water works nicely as a finisher as it brings a creaminess with it. Think of how risotto leverages the starch extracted from rice to make its sauce seem creamy without using any cream. Unfortunately, at home, we only cook up one batch of pasta at a time, starting with fresh water from the tap. How do you increase the starch content of pasta water at home, when you are only going to make one batch of pasta? Use less water! If you only use two quarts of water, you’ll end up with twice the starch content compared to if you used four quarts of water.
The new technique is also faster. I find that the dry pasta needs to be cooked an extra minute or two beyond the package directions. But, the fact that two quarts of water comes to a boil much faster than four or five quarts of water more than makes up for the difference. It also saves some energy, which is good for the utility bill and your carbon footprint.
The Technique
The technique is simple. Add two quarts of water to a pot and bring the water to a boil. Add some salt to the water. Add the dried pasta to the water and stir vigorously. Just like with the traditional technique, you need to stir vigorously as soon as you add the dried pasta, to ensure the pasta doesn’t stick together. Let the water return to a boil, stir again, cover the pot, and shut off the heat. After one more minute, stir vigorously one final time and cover the pot again. Note, I’m often distracted and it’s 2, 3 or 4 minutes later when I give the final stir. The timing of the final stir seems to be quite forgiving. Kenji suggests checking the pasta for doneness 2 minutes before the time suggested on the pasta package. For the pasta varieties that I cook, I find that this technique either matches the timing on the package perfectly, or it takes a minute or two longer. Depending on the brand and shape of pasta you cook, your mileage may vary. To test the pasta for doneness, fish out a single piece and bite it. You’re looking for the pasta to be fully softened, but still have that al dente bite. If you find that there’s a chalky center, give the pasta another minute or two and retest.
When the pasta is ready, scoop out a cup of pasta water and then drain the pasta. Immediately toss the pasta with whatever sauce you have prepared. You want the wet starch clinging to the sides of the pasta to help incorporate the pasta with the sauce. If the recipe calls for it, or you find that the sauce can use it, use a splash or two of the reserved, seasoned, starchy pasta water to finish the sauce.
Salt
A commonly held belief is that pasta should be cooked in water that tastes like the ocean. I used to be in that camp. I started to think a little differently when I heard a chef say that you should use much less salt, making the water taste like soup and not the ocean. His logic was that soup is delicious while the ocean is not. I didn’t buy his argument, but when I started using pasta water to finish sauces, it made sense. If you use a ton of salt in your pasta water and send it down the drain after cooking your pasta, such a small fraction of the salt actually goes into the pasta, it leads to a well-seasoned dish. But if you use a few ounces of that ocean flavored water to finish a pasta sauce, it leads to an overly salted final dish. Kenji only uses one teaspoon of salt for the two quarts of water in his recipe. His recipe for a ricotta based pasta sauce uses a full cup of pasta water. I rarely use that much pasta water to finish a sauce. I’ve found a tablespoon of salt for the two quarts of water works better for me. If I know I’m going to be using half a cup or more of that pasta water, I’ll use less salt in the water. Note, also, I use Diamond Crystal salt, which weighs less per volume than most other salts. Check out my post A Teaspoon of Salt is Not Necessarily a Teaspoon of Salt if you are interested.
Caveats
There are a couple cases where you should avoid this technique, and they are both pretty obvious. The first is not to use this technique with fresh pasta. Where dried pasta needs to be rehydrated, fresh pasta needs to be cooked. Traditional methods using a high volume of water and a rolling boil are best for fresh pasta. The second case is when you cook long shaped pasta. With long shaped pasta, and only two quarts of water, the ends of the pasta won’t submerge until the submerged portions soften up. Also, you won’t be able to stir the pasta properly early in the cooking process. Again, when cooking long shaped, dry pasta, the traditional methods are still superior.
