Recipe app Firestore data model questions

Hello everyone,
I am trying to recreate a recipe app as part of learning Firestore. I have already created it using the Firebase Realtime Database and it works well. Firestore is a different paradigm where things are kept documents instead of just raw JSON.

Can someone explain the paradigm for me. I don’t want to create a bunch of reads and such with this new Firestore structure.

Here is what I started with:

Documents:
Containers
     uuid
          name
          size
          type
Recipes
     uuid
          name
          time to prepare
          ingredients
               uuid: amount, 
               uuid: amount, 
               uuid: amount
Ingredients
     uuid
     name
     units
     type

I just want to make sure that I can update ingredients and also update the recipe that contains the ingredient. Say I wanted to change flour from kilograms to grams. I would want to cascade that throughout the recipes. I know someone will say why not use functions. But I want to make sure that when I structure the basic recipes, ingredients and such so that I am not going to be charged for performing a ton of document reads etc.

I know there must be a best practices for this type of exercise but I have only found “how to create” things in Firestore. Nothing about best practices.

Any help you can give will be appreciated.

Thanks,
Jamie