You get this trophy when you have collected 50% of the ingredients available.
This means 34 different ingredients.
for me it happened after:
- finished the cities of Arba, Caliburgh, Colissea, and Sylvea.
- having done Fire Place, the training Island Once
- and having ran through both Arba levels for grinding
- and having ran through Colissea for grinding a bit too
This does not mean you have to grind for levels.
It is just what happened for me.
It actually popped after my second Fire Place grotto,
which means you don't always get the same loot from those.