Ok so... I got the achievement and I don't know _exactly_ how, but I did keep a tally of everything I did. Previous guides suggest that before the change to 30, all 8 cooking skills and 3 food related jobs were required. I therefore did _everything_ I could think of that related to food in the game and have included it below. I don't know if all of it is necessary, but the achievement popped as I bought my 4th beef wellington after doing everything else on this list with 4 turns left to the final exam :)

Food Eaten:
Beef Burger x4
Mac & Cheese x 3
Apple Pie x 3
Dried Snail Candies x1
Dragon Fruit Juice x1
Carrot sticks x3
Defrosted Fish x3
Energy Candies x1
Mushroom Risotto x1
Gratin Duphanois x3
Beef Wellington x4
Chicken Salad x4
Coffee x1

Recipe Books Bought:
All of them (I don't remember what they are called, but its all of the books for sale at the cafe)

Jobs Perfected:
Lemonade seller
Kitchen Assistant
Waiter
Buying groceries (not sure if necessary? its just food related?)

Skills Perfected:
Basic Ingredients
Knife Skills
Meat Dishes
Fish Dishes
Pasta
Desserts
Culinary Mastery


The achievement is clearly bugged, so I don't know if this will help you, but yeah thought I'd post just in case! :)