Any time a chef sends a dish up in a dramatic blaze (using alcohol, generally).
Sakai defeating Chen to claim the title 'King of Iron Chefs', and then immediately after defeating Alain Passard in the final (regular) Kitchen Stadium battle.
And he beat Chen in a lobster battle, a theme ingredient he'd gone 0-3 with.
Using the cursed ice cream machine to make Trout Ice Cream and having it taste good (even though he didn't win the battle), is one for Sakai.
Immediately preceding the final battle (and sadly cut from the Food Network broadcast), almost all the challengers on Iron Chef (over three hundred) entered Kitchen Stadium one last time. (The only one not there was the by then deceased Rory Kennedy.)
Sakai defeating Morimoto to get into the finals. With a perfect score.
After Morimoto had racked up a perfect score the week prior in the final "regular" challenge match in Kitchen stadium, to boot.
Michiba defeating Chen to win his second Mr. Iron Chef title. On his 65th birthday. In his final regular battle.
In the eggnog/ice carving battle of Iron Chef America, Morimoto had a smoker made of ice.
He then proceeds to bring it out again later in another episode.
In Battle Cauliflower of Iron Chef America, the challenger actually challenged Iron Chef Symon without sous chefs. Once the Iron Chef realized this, he kicked his own sous chefs out of the kitchen. They went 60 minutes and made 5 dishes on their own.
And then Iron Chef Symon goes Serial Escalation and finishes early enough to have champagne with the judges. And yes, he did win that one.
Older Than They Think: Sakai did the same thing when Masanobu Watabe challenged him without sous chefs (though that's partially subverted as Watabe is such a demanding Jerkass that no one would work for him. Still a CMOA for Sakai, though).
Sakai started with sous chefs, and only kicked them out after commentary kept making reference to it. Watabe even said Sakai didn't have to do it, and afterward Sakai said he didn't want to do it again.
Chen won the yogurt battle against a French-Italian-Japanese chef, despite the fact that yogurt is hardly (if ever) used in Chinese cuisine and being under huge pressure the entire battle while his opponent was pretty relaxed. The look on his face when he won reflects just how surprised he was to beat such odds.
The Ohta Faction: Led by Tadamichi Ohta (who, himself, defeated Sakai), a league of traditional Japanese chefs who hate Morimoto with an intense passion and it might not just be kayfabe; they wish nothing less than to see Morimoto destroyed due to Morimoto's... unique interpretation in everything he cooks. This league's chefs, internationally renowned, have repeatedly challenged Morimoto specifically to try to prove to him that traditional cuisine trumps new dishes invented on the spot — Morimoto winning 4 out of 5 of the duels.
The first US Challenger, Ron Siegel, challenging Sakai, one of the best Iron Chefs when it comes to seafood, in a "lobster battle" and winning. (In a book on Iron Chef that sold in the US, some of the recipes Ron used are published in it.)
Even better, he won all four votes and had a near-perfect score, while having sous chefs that couldn't speak English.
Chopped Grand Champion Madison Cowan teams up with Lance Nitahara and judge Amanda Freitag to take on Jose Garces on Battle Kale was plain awesome on many levels.
First, Lance Nitahara teams up with Madison Cowan. Yes, thatLanceNitahara that gave away half his winnings to his opponent.
Next, Amanda Freitag teams up with Cowan setting up a revenge/grudge match against Garces because she lost to him on the 2nd season of Next Iron Chef.
Third, Alton talking smack to Cowan about "being in our house," with different rules and formats, and how he's not going to have an easy time in Kitchen Stadium.
Finally, the result. Madison curb-stomps Garces in both taste and originality, effectively giving Madison the win!
The "Fusion" episode of The Next Iron Chef: Redemption forced the chefs to create dishes pairing unlikely foods. Amanda Freitag got calamari and marshmallows, a pair that disgusted all the other chefs, too. And then she won the challenge with it.
Judges: We were dreading this combination, actually, but you did something amazing with it.