I don't know the full answer, but here are some examples I've seen of a Mizahar cook (
Orin Fenix) likely utilizing philtering in his recipes:
- Brining pork
- Fermenting vinegar
- Grog recipe
- Mayonnaise Recipe
- Utilizing mold to create soysauce
- Preparing medical tea (most medicines off the pricelist require philtering)
- Using cheesecloth as a filter
All of the above were taken from his CS in his list of cooking lores.
Also off the top of my head, I could imagine something like jam or jelly requiring gelatin might have use for philtering.
EDIT: Yeast too (for making bread) might require some knowledge of philtering.