Great idea! This could also work well for ingredients you already have on hand at home and want to use up.
Weāre actually working on a new way of building meal plans right now that will include a search feature. It wonāt be as powerful as you suggest for its initial release (you will only be able to search for recipe titles instead of ingredients within a recipe), but with improvements it could work in the way that you describe!
Keep an eye on the community later this week - Iāll be posting an overview on the new builder and will be looking for feedback. Thanks @rtoyen 

Another benefit to a field for recipe notes is possible feedback on how people are using the recipes. Iāve seen this sort of thing used really well on other recipe sites to kind of ācrowd sourceā ways to improve or clarify recipes.
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