You´re missing the point. Soma´s opponent was there because he´s known as the copy-monster. Stealing any cook´s cooking and improving upon it.
Soma won because he broke he either broke the rules, or because he was unpredictable because ... BECAUSE!
I actually had hoped Soma would just cook whatever he planned to and not do anything special, then winning, because "it tastes better", showing his pure cooking prowess. But that didn´t happen.