One of the more common misconceptions about cast iron cookware is that you shouldn’t cook any acidic foods in your pans. While it’s true that simmering acidic ingredients in cast iron for longer periods of time can impart a metallic taste and/or affect your pan’s seasoning, you can safely cook lots of things—including our shakshuka recipe below—without having to worry about off flavors or damaged pans.
Here's how to do it:
When cooking acidic foods in cast iron, it’s best to keep the cooking time below 30 minutes; any longer and your sauce might begin to taste metallic, or your dutifully maintained pan might lose some of its seasoning.
When cooking acidic sauces, stews and the like, it helps to know the general pH level (i.e. acidity) of your ingredients. Canned tomatoes—a common ingredient for many sauces‚ have a pH of around 4, which is less acidic than wine (3 to 4), vinegar (2.5), and citrus juice (around 2). The takeaway? It’s safe to cook tomato- and wine-based sauces in cast iron, but you should save the vinegary pan sauces for stainless-steel pans—or dilute the vinegar (or citrus) with water or stock.
We always advocate cleaning your cast iron pans as soon as you can after you’ve finished using them, but it’s especially important to do so when you’ve cooked higher-acid foods in them. If you forget to do the dishes, don’t worry: Even if your pan’s seasoning takes a hit, you can restore it with regular cooking, or a good re-seasoning.
¼ cup extra-virgin olive oil
1 medium onion, diced
1 large or 2 medium red or orange bell peppers, seeded and cut into ⅛-inch strips
1 cup cherry (or other small) tomatoes, halved
2 garlic cloves, thinly sliced
1 tablespoon harissa
One 28-ounce can whole tomatoes, crushed with your hands
1 tablespoon red wine vinegar
Kosher salt and freshly ground black pepper
4 large eggs
Optional toppings: chopped cilantro or parsley, crumbled feta, hot sauce
While a well-seasoned skillet can absolutely stand up to acidic ingredients if you follow the instructions above, we wouldn’t recommend cooking shakshuka in a brand new pan. When is a skillet ready? Reliable non-stick performance and the darker patina that comes with seasoning earned through cooking are each signs that you’re ready to give acids a try.
In a well-seasoned cast iron skillet, heat the oil over medium-low heat. Add the onion and cook until softened, about 5 minutes. Add the bell peppers, cherry tomatoes, and garlic and cook, stirring frequently, until the peppers are soft, 10 to 15 minutes.
Add the harissa and tomatoes, bring to steady simmer, and cook until thickened, about 10 minutes.
Crack the eggs into skillet and cover the pan with a lid (or transfer the skillet, uncovered, to a 375°F oven). Continue cooking until the egg whites are set, 5 to 7 minutes longer.
Serve promptly and use a wooden utensil or paper towel to immediately remove tomato sauce residue from the skillet. (Be careful! The pan will still be hot.) When pan has cooled enough to handle, rinse well, wash with a firm cleaning brush, dry thoroughly, and apply a dab of Field Seasoning Oil.
The key to reliable, use-it-every-day cast iron is seasoning: a smooth, well-seasoned skillet will clean up with just a quick wash, and produce natural non-stick performance every time. Apply a dab of Field Seasoning Oil after cleaning to protect your skillet and build durable non-stick seasoning.
