Size is not really an issue when you're dealing with IDs and some text in a (I assume) single-user solution.
Repeating fields in FileMaker are a relic from pre-relational times, and are to be avoided for storing real data
(as opposed to runtime data, meta-data (layout graphics) etc.). Any kind of reporting with repeating fields is
bound to become a nightmare for all but the simplest applications. A proper setup relational system, on the
other hand, is powerful and flexible tool, and is easy to implement.
The normalized relational structure for your solution uses three tables:
Ingredient – each record is an ingredient
Recipe – each record is a recipe
Recipe_Ingredients (or “Details”, as you put it) - each record is (an occurrence of ) a specific ingredient for a specific recipe,
as indicated by two foreign keys (IDs from Recipe and Ingredients table); define additional fields here to add measurements,
comments, or a sort field to put the ingredients in the proper order for preparing the recipe.
Now in a Recipe layout you could use a cartesian portal to choose from the list of available ingredients to add to your recipe
and see the ingredients used in this recipe in a second portal, where you can comment and sort them.
In an Ingredients layout, you can see which ingredients are used in which recipe(s), compare a sum of measurements used
with the stock in hand and have you give an alert when it's time to go shopping.
You see, this relational structure allows for a lot of flexibility, and the reporting features as described are hard to impossible
to realize with repeating fields.
What Oliver Stroh is suggesting is called a many to many relationship and definitely, it is the way to go. You may want to look over this demo file for ideas in how to implement a many to many relationship. The "check boxes" layout in this demo is vary similar to what he describes with a cartesian join relationship (X operator instead of =). You'd just add a portal to the join table to list the selected ingredients and fill in the additional details on how they are used.