Welllll...according to the lines on my cooktop, and I don't know if they are representative of the usable area or not because I didn't read the manual, but I think they are, I have an 8 1/4" diameter cooking surface. Yesterday I was boiling sugar syrup stuff for candy in a pot with a 10" diameter bottom. Nice slow sticky bubbles. The goo wasn't that deep, so I don't know if it matters that this was a roasting pot instead of a saute pan.

I think the lines on my cooktop are representative, because when the goo first started to boil, it was not quite the width of the pot. But very quickly, the whole mess started to boil. I think that whatever material the pan is made of will make the difference at least as much as the type of pan. Cast iron is really responsive.

Just like with regular electric, it might take some preheating if you want an oversized pan to be even from the getgo, I think.

Now, I don't saute much, so I don't really know the process, but it's sort of like wokking, isn't it? Fast, high heat, in a preheated pan? Just a saute pan is flatter? I can quickly preheat the sides of a wok with induction, so I'd guess that you could preheat the excess sides of a huge saute pan just as well. And my little candy experiment convinced me that a few inches of excess pan will catch up really fast, at least it will if it's cast iron on a 25 year old cooktop.

Thanks for the response Fori.

I got a little smarter over the weekend after purchasing a Lodge Logic 9" pan (i.e., about an 8" bottom diameter). Tried cooking over a 7" diameter disk and see how it would work. The edges heated up but the 7" core was definitely hotter. (It was a mess with the eggs. Apparently the pre-seasoned pans don't retain their seasoning well. I tried cleaning it with Alton Brown's technique of rubbing oil and kosher salt with a paper towel. The towel shredded and it was difficult to remove the salt and shredded filaments. Looks like I'll try seasoning via bacon fat with a tilted upside-down pan in the oven.)

The largest burner on my Fagor is 8 11/16" so I finally played it safe and ordered a Demeyere ($$$) saute pan (9.4" x 8.7") instead of the larger (11" x 10.2") pan. I'll retry with that on a smaller burner as well since different cookware may be more usable with a smaller diameter burner than others.

Season before it gets too cold to leave the windows open!

After proper seasoning, you can wash with soap and water and forget about all that weird salt and paper towel business...

There are some good threads here on cast iron.

Your plan to test some more is a good one. Let us know!

A "pre-seasoned" cast iron pot is not the same as a "cured" pot. To cure a pot you can use it for many years and it eventually will become cured. How fast it cures is dependant on your cooking techniques and frequency of cooking. Or.......... you can season it "multiple times" at a high temperature (450 to 500 degrees F) to rapidly cure your pot. Follow directions listed in other threads on this forum as Fori suggested. Once its cured it will no longer be reactive (oxidize or rust) and become virtually stick free.

Before re-seasoning your pot, I suggest you clean it well with Bar Keepers Friend and a good stiff nylon scrub brush. BKF has special cleaning properties that work well in cleaning a pot just before seasoning. After your pot is cured avoid cleaning with BKF.

Dan