For me, it was my de Buyer carbon steel roasting pan.
Previously, I just effin’ hated roasting in the oven. Food sticks to stainless steel pretty well in the first place – much less when you give a good couple hours to get baked on. So I loved roasted food, but hated roasting it.
I have lots of other cookware I love, but this was the piece that most changed how I cook.
Large hotel pan. I wouldn’t make corned beef (corning and cooking) without it. Use it to steam pastrami as well. Can use it as a warming tray. Can roast with it.
Interesting question. Not sure about changed my life, but a real game changer was our 1st large ceramic coated dutch oven (early '00s) opened up so many other food possibilities than before it has to be the winner in our kitchen.
My 1st good chef’s knife would be #2.
Our 1st long handled tongs #3.
I should add that a kitchen scale was a game changer for me. I’m actually upset that recipes don’t generally use weight measures. It’s so much easier to measure grams/ounces than cups and teaspoons.
Probably the cast iron frying pan acquired from Goodwill back in college days. Stir frying was unknown where and when I grew up.
I’ve used a wok more than the cast iron for many years, but it was the skillet that changed the way I cooked and ate.
So did a couple of deBuyer saute pans of varying sizes…Changed how I cooked many proteins and otherwise.
But…I’d have to go with the high heat cooktop from Blue Star…creates enough BTU for almost everything I want to do (except in a wok, as it can’t be used directly on the fire and doesn’t get hot enough with the stand). The Blue Star burners made the deBuyers really shine.
This is interesting, though not from a cooking standpoint.
Ever since I used the link to a certain knife sharpener posted on this forum, I’ve been fed a constant stream of ads for the same in my browser. I mentioned a wok today a few posts above, and the knife sharpener ad has been replaced by one for a wok.