Forgotten Tales

It probably has a simple answer but i was away for nearly a year and forgive me if this is a silly question but how do you cook them?

Welcome back!

Go to map 4, 1. There is a cave in the top left corner.

First level is a green cave where you kill the dogs to get the raw swamp meat.

The next floor down is the ptery cave.

You want the floor below this. It is the cave that contains mystic dragons. Go to the top right corner and near the NPC is the oven to cook the swamp meat. It has something like a 50% chance rate, so I would drop more than you need to save making more than one trip.

So i found the place, cooked 7 meat just because of curiosity and they all spoiled. Did i do something wrong or i was just unlucky?

it seems a very long grinding is waiting for me

Just unlucky, I'm afraid.

Rotten Swamp Meat - PU!!!!!
Keep trying, good luck.