The Best Way to Boil Green Beans

Years ago, I stumbled across a tip in Harold McGee’s indispensable tome On Food and Cooking (1984) that described how heavily salted water speeds the cooking of vegetables. According to McGee, the key is to cook vegetables in extremely salty water—so salty that it has the same 3 percent concentration as seawater. I’d never acted on it since it translates into 2 tablespoons of salt per quart of water—an extraordinary amount, given that I usually throw that much into 4 quarts of water when blanching vegetables. Now, with loads of boiled green beans on the horizon, I decided to finally give it a try.

I boiled 1½ pounds of green beans in a solution of ½ cup of salt and 4 quarts of water alongside another batch with just 2 tablespoons of salt in the same amount of water. Sure enough, the beans in the heavily salted water were tender a full 5 minutes before the beans in the lightly salted water. They had also retained their vibrant color, while the other beans had faded to a drab olive.

This was a neat discovery, but the one I made when I took a bite of the “seawater” beans was even more important: They tasted incredible. The heavily salted water had given them a meaty, highly seasoned, and intensely green-beany flavor—and without making them overly salty. The beans that had cooked with just a little salt, on the other hand, barely tasted seasoned at all.

What’s so magical about supersalty water? According to McGee, when vegetables are cooked in salted water, sodium ions displace some of the calcium ions in their cell walls. Calcium ions strengthen pectin—the glue that holds plant cell walls together—by allowing it to form cross-links, and the ions’ displacement prevents that cross-linking and causes the vegetable to soften. (It is for precisely the same reason that we like to brine dried beans in salt water: The displacement of the calcium ions in their skins softens them and prevents them from bursting during cooking.)

But ½ cup of salt was a lot to use for one dish. I wondered if I could get the same effect with less, so I tried going down to ¼ cup of salt per 4 quarts of water. The beans took slightly longer to tenderize, lost a little of their color, and were no longer as well seasoned or as flavorful; clearly you need a strong salt concentration to get enough sodium to infiltrate the beans’ sturdy skins. The solution (pun intended)? Keep the concentration the same but decrease the volumes of water and salt. Just ¼ cup of salt in 2 quarts of water did the trick and felt like a reasonable amount for such tender, vibrantly colored, and deeply flavorful green beans. 

To highlight the beans in a salad, I created a few variations: a Mediterranean composition using mint, parsley, feta cheese, and tomatoes; a French-style version with Dijon, capers, and tarragon; and a Southeast Asian–influenced salad with fried shallots, carrots, and peanuts. Not only were these some great salads, but I also had a terrific new blanching technique that I could apply to other vegetables as well.