If you own a cast-iron skillet , then you likely already know that this tool is the ultimate multitasker in the kitchen. It’s incredibly durable, it channels heat to perfection, and it can be used to cook almost anything… but maybe not quite anything.
Tomatoes are often discussed in negative terms among cast-iron enthusiasts; rumor has it that tomatoes can corrode cast iron and damage these reliable workhorse skillets, while the iron imparts an unpleasantly metallic taste to tomato-based sauces and braises.
So what’s the real story here? Is it okay to cook tomatoes in cast iron, or is it best to avoid any interaction between the two?
To get the answers to these questions, we asked a group of professional chefs and food scientists to share their thoughts on the controversial relationship between tomatoes and cast-iron cookware.
The acidity of tomatoes makes them challenging to cook in cast iron
Anyone who’s ever eaten a tomato or cooked with tomatoes can verify that this fruit is quite acidic. As it happens, the tomato’s acidity is precisely why doesn’t work well with cast-iron cookware, especially for long cooking stretches.
"Cast-iron skillets can handle a small amount of acidic fruit at a time. As long as you don't cook tomatoes for longer than 15 minutes or so, the acidity from the fruit won't destroy the seasoning of the pan," says director Craig Wilson of Gardener’s Dream , whose gardening expertise includes substantial knowledge of tomatoes. But if you want to make a slow-simmered sauce or a tomato-based stew, Wilson insists that "you'll need a different kind of pan for that."
The longer the tomatoes cook in the skillet, the more likely it is that the "acidic reaction [will] eat away at the seasoning of the pan,” says CEO Mark Haas of The Helmsman Group , which consults with food brands on food-science matters. Haas goes on to tell us that "cooking acidic foods [in cast iron] will cause uneven heating in your cookware and [will] require you to re-season your pan."
To avoid these problems, use a stainless steel skillet or an enameled cast-iron skillet (like a Le Creuset) in lieu of a "naked" cast-iron pan.
"Enamel is non-reactive, as is stainless steel. That’s why so many brands offer enameled cast iron and stainless steel-clad iron or aluminum cookware," explains chef-instructor Jay Weinstein of the Institute of Culinary Arts .
Even if the tomatoes do strip away some of the iron, it won't pose a threat to your health
Since the acid from tomatoes can impact the seasoning and overall condition of cast iron, one might conclude that, when tomatoes are cooked in cast iron, the iron can seep into the sauce or soup or braise. Owner and recipe developer Jessica Randhawa of The Forked Spoon tells us that this is a legitimate possibility, but that there’s no health risk at play here, especially since we’re talking about very slight quantities of iron.
“When cooking tomatoes in cast-iron cookware for an extended period, the acidity of the tomatoes does slightly leach trace amounts of iron. [But iron] is found in almost every over-the-counter multivitamin," Randhawa assures us.
The iron can, however, affect the flavor of your tomato-based dish
"In general, I don’t like to cook tomatoes or anything with a high acid content in cast iron, [as] it will change the dynamic and flavor profile,” chef/owner Isaac Toups of Toups’ Meatery in New Orleans tells Southern Living .
Several of our consulted chefs agreed that cast iron can leave an unpleasant flavor layer in tomato-based dishes. The "naked" cast-iron cooking surface of an unenameled skillet can cause "acidic foods to become discolored and acquire a metallic taste," says Weinstein. In terms of the discoloration, Weinstein describes it as “brown tomato sauce and purple-black wine sauces.”
Executive chef Bin Lu of Blue Rock Restaurant and Tasting Room in Washington, Va. does sometimes like to cook tomatoes in cast iron, but only in specific circumstances: “If I'm going to use tomatoes with cast iron, I try to stick to hard sears—things like blistered cherry tomatoes that are cooked hot and fast, maybe tossed with a little bit of garlic and herb and taken out of the pan as soon as possible. Seared green tomatoes work well because they don't give off as much liquid as ripe tomatoes. If, for whatever reason, I have to be able to add a liquid to the pan, I stick to cream sauces—again, cooked as quickly as possible, no slow sauces here—to mitigate the effects [of the tomatoes’ acidity]."
If you’re determined to cook tomatoes in cast iron, keep your skillet well-seasoned
Unenameled (or "naked") cast iron isn’t a prime option for tomato cooking in general, but if you really have your heart set on a one-pan dinner featuring your cast-iron skillet, then said skillet "needs to be well seasoned first," says chef and recipe developer Deborah Rainford of Savvy Bites . "Well-seasoned cast iron can definitely stand up to acidic ingredients without any problems."
season a brand-new cast iron pan
(or to re-season an older pan), "rub a neutral oil, usually canola, onto the pan's surface, and bake it in a hot oven for about one hour. Turn the oven off, and let the pan cool in the oven completely. For a cast-iron pan to be considered well seasoned, it must go through the seasoning process about six times,” Rainford tells us.