One of the possible reasons is given that SK wants a cookbook by Mehek's mother. That makes me wonder, if Mehek's cooking skills are only limited to producing recipes in that book to the T? If that is the case, she is just good at following instructions.
A good cook (chef) is not just good at repeatedly create same dish but also inventing new ones. Good cooking is as much an art as it is science where previous results can be precisely reproduced.
I also wonder how can Mehek win the competition based solely on that book as the competition kept on throwing surprises and her mom could not include all the possible permutations combination. So it means that book might be what started her journey but her skill is beyond a book.