Why did my sweet potato hash turn soggy when frying in a non-stick pan, and crispy in a cast iron?

Question

I was making a sweet potato hash for pizza topping the other night, and tried to fry the first batch in a non-stick pan. The hash never crisped up and was soggy, so I ended up mashing it instead. The next batch I fried in my seasoned cast iron, and it crisped up like a good hash.

Does anyone know why this happened? To me, it doesn't make a lot of sense if both the pans were equivalently hot with the same amount of oil to fry in. The hash in the non-stick pan also seemed to absorb more oil, but again, not sure why.

Details:

• I used a similar amount of bacon fat to fry both batches in
• The hash was seasoned with garlic, salt and various spices (no onion)
• Similar heating levels, preheated both pans
• No lids were used
• The non-stick pan is a nice Teflon coated Calphalon, and has pretty good heat retention; I use it for stir fry successfully

Answer 1

The theories that have come out in comments are most likely right on. Cast iron is special in how well it retains heat. Give cast iron ample preheating time, and you can drop in cold food without a significant drop in the temperature of the pan. That equals crispy. Even a pretty good and heavy non-stick pan is not going to give sweet potatoes the kind of crisp you can achieve with cast iron.

You mention higher sides in the non-stick pan. That alone probably wouldn't make much of a difference, but considering that you're already seeing a greater drop in temperature as you put in the potatoes, the higher sides would hold in more moisture in the cooler pan. That is not a friend of crispiness.

You say that you preheated both pans to about the same temperature. I actually hope your memory is a little off on that :) One of the great joys of cooking with cast iron is that you can and usually should pre-heat it to a quite high temperature without damaging the pan. Teflon, on the other hand, should never be preheated beyond a very moderate temperature for a very short time. Some people go so far as to say that you shouldn't preheat it all. So if your beginning temperatures were about the same in the pans, they shouldn't have been. After you put in the potatoes, forget about it. You'll never get the same kind of crispy sear with a teflon pan as you will with cast iron, even if you don't know how to best exploit the advantages of cast iron.