In order to advance in rank, you have to trade the guildmaster in Windurst Waters an item. In this case, you'll need a Salmon Sub, which can be bought in Windurst Waters itself, or synthed:
Earth crystal
Crying mustard, black bread, la theine cabbage, apple vinegar, smoked salmon, and mithran tomato.
EDIT: There are 2 guildsroom, 1 that holds the guildsman, and the other that sells guild items, you can buy the sub from the guild salesroom, and trade it to the taru in full chef gear in the other.
Edited, Sun Apr 23 15:52:31 2006 by Kagapi