For this achievement you will have to have Rucha cook the Heaven and Earth dish. Rucha must be at IC Level 6 and you must complete the additional Cooking Upgrade Quest.
This quest can only be started after you finish the game and load your save. To start the quest you must talk to Rucha in Halgita. She will then request several items from you:
1 Sliced Rare Salmon- Dropped by the Mantifish enemies in the Port Zala section of the Seraphic Gate.
2 Prehistoric Meat- Can be bought from the Halgita General Shop
3 Pieria Mushrooms- Can be bought from the Halgita General Shop
3 Sapran Green Peppers- Can be bought from the Port Zala General Shop
Once you collect all the items, talk to Rucha in Halgita and she will then learn to cook more dishes, including the Heaven and Earth Dish.
Now for the actual Heaven and Earth dish you will need these items:
1 Dragon Meat- Dropped by Inferno Gluttons in the Dragonbone Shrine section of the Seraphic Gate.
2 Sliced Rare Salmon- Dropped by the Mantifish enemy in the Port Zala section of the Seraphic Gate
1 King Egg- Dropped by the small blue bird enemies in the Oradian Dunes section of the Seraphic Gate
Note: Make sure you save before trying to make the dish as you can fail very easily.