Article: Fond of Cast Iron?

Many recipes call for frying, searing, sauteing, or otherwise touching meat and vegetables to hot metal in an effort to promote caramelization. No one is quite sure what the hell goes on during caramelization... but nearly everyone with a shred of culinary skill agrees that caramelization is a very good thing.

Why?

Flavor.

Caramelization
Caramelization is a chemical process that oxidizes complex sugars into simpler sugars—the net result of which is nutty-tasting, brown and sweet goodness.

Caramelization is the reason grilled foods have that certain something extra going on. It is also why roasting on higher heat is generally preferable to simply baking. When your meats and sweeter vegetables or tubers get browned, it means that they have caramelized.

Caramelization in liquid form
It's only natural that chefs have sought to harness the flavoring power of caramelization for use in things other than grilled and roasted foods. Adding caramelization flavors to soups, sauces, pilafs, and other liquidy dishes is often what sets these dishes apart from their run-of-the-mill cousins.

How is this accomplished?

Fond
Fond, which is French for "base", is the browned bits of crusty juice, fat, and flavor that form on the bottom of a pan when searing or frying meat, vegetables, or tubers (see photo at right). Fond is absolutely essential when making a pan sauce (note: use stainless steel cookware, not cast iron, for pan sauces). Fond also allows the cook to add additional flavor elements to slow-cook liquidy recipes (perfect for the dutch oven) like chili, soup, marinara sauce, stew, and more.

As mentioned above, you should not use cast iron cookware if you are after a true pan sauce. These sauces involve developing a rich layer of fond, and then deglazing the pan as the base for the sauce. Deglazing for a pan sauce is typically accomplished by adding liquid to the hot pan which has the effect of lifting the fond. Common deglazing liquids include lemon juice, white wine, red wine, vermouth, tomato juice, and broth.

If you deglaze a cast iron pan, you are likely to remove the seasoning. This not only harms the pan, but adds black bits of petrified grease to your recipe: a losing proposition on several fronts.

Harvesting fond from cast iron
You can effectively remove the developed fond from cast iron through more subtle means than high heat and acidic liquids.

Adding aromatics (onions, carrots, celery, etc.) is usually enough to remove fond from cast iron. You can also add broth or other liquids (as called for in the recipe) to a cast iron pan that already contains other ingredients (e.g. the meat), or is not hot enough to deglaze (no hotter than medium heat, as a general rule).

Cast iron cookware is unique in its ability to provide a non-stick surface for searing meat and vegetables, yet at the same time allowing for the development of fond. This allows dishes like chili and spaghetti sauce to cook all day in your dutch oven without sticking to the bottom, but also allows you to add the richness of caramelization.