I personally had never heard of it, but after doing some research online, I found another set of instructions that called for boiling potatoes in the pan before seasoning:
After boiling potato peelings for 15
minutes, the skillet had a nasty
slurry of grey looking sand in the
bottom Once the skillet was heated,
the pores were opened, and the
starchy/water mixture was able to draw
out oils and dirt that I was not
capable of getting to through normal
washing. I fully do not understand the
science behind why the starch/water
mixture did this, but the experience
was enough to convince me of the need
to do this. So much in fact, that I
did this process twice on each
skillet.
I read a few too many web pages while researching this, and didn't save all of the links, but I did notice a few things:
Some of the posts kept switching between saying cast iron and carbon steel; both are typically seasoned, but they're different materials, so I don't know if it's recommended for both, or if people were mixing things up. (I only have one carbon steel item, a wok, which I got second hand, so had already had its first seasoning).
Some of the posts mentioned boiling potatoes for 15 minutes, other mentioned frying potatoes as the first thing to be cooked in the pan (in oil), some mentioned cooking them 'til they burn. The boiling potatoes ones also mentioned it works for cleaning stainless steel pans.
Some mentioned peels specifically, others say that you can use any part of the potato ... if it's the starch that's of interest, I'd think the middle would actually be better, but I'm guessing that the peels were considered waste, and so considered a less valuable item; I'd be inclined to just use one potato, dispatched with a peeler, if you were trying to avoid wasting potatoes you weren't going to eat.
Induction cooking works by generating an electric current in the metal cooking vessel and converting that current into heat, which requires a resistive material (i.e. a poor conductor).
It's a bit of a catch-22, because you need a good conductor to actually distribute that heat. This is why some of the best induction cookware is clad metal - two layers of (magnetic) steel around an inner layer of highly-conductive aluminum or sometimes copper, sometimes layered multiple times this way. The thick magnetic sheets generate heat, and the thin conductive sheets transfer it.
Thicker metal means that the surface is slightly farther away from the magnetic field source, but also has significantly more resistance (since resistance is proportional to length, and we are talking about doubling or even tripling that), so theoretically it should be much more effective at converting the electric current to heat, and heat up faster.
The disadvantage of a thicker metal - assuming that there is no additional heat transfer material - is hot spots. This doesn't matter at all for a skillet, but if you're trying to cook with, say, a cast-iron stock pot or dutch oven, you'll find that the hot spots are even worse on an induction cooktop than an electric or gas cooktop, since the surface heat is generated very rapidly but takes forever to spread.
Carbon steel is a pretty good compromise, which is why it's generally the material of choice for woks, and that's the material I'd choose for an induction cooktop for any vessel other than a skillet or frying pan (assuming I had to choose a single material; again, copper/aluminum-clad stainless steel works better). For pans/skillets, you want the heat to stay focused on the surface, which makes heavy/thick cast iron a better choice.
I can't honestly say that I've had much experience with forged iron, but all my instincts are telling me not to bother with it because it would be combining the worst of both worlds - lower resistance at the surface but still relatively high resistance up the sides. The only caveat to this would be a possibly significant difference between the magnetic susceptibility/permeability of forged vs. cast iron, but this is likely going to vary from vessel to vessel anyway (not all cast/forged iron is the same) so I think your best bet there is to try sticking a magnet to it. If it sticks much harder to the forged than cast iron (doubtful) then it might be good for surface cooking; I still wouldn't choose it for a larger pot.
Best Answer
Cast iron and carbon steel (aka “forged iron”) are fairly similar. Both require seasoning for best results, and can produce a decent non-stick effect when properly seasoned; both have high heat capacity but mediocre heat conduction; both are quite durable. Carbon steel is somewhat more lightweight than cast iron, making it more versatile (you wouldn’t want to flip the contents of a large cast iron skillet one-handed). Additionally, modern cast iron pans are rough-textured, which can make them more difficult to effectively scrape with a spatula.
I own and use both. These days I use carbon steel much more than cast iron.