The ingredient editor was never intended to be shown to non-site-admins, so it may appear to be a little rough around the edges (though it works like a champ). It's worth noting that anything that appears in yellow is "admin-only", meaning, it's intended only to be see/used by a site administrator.
This editor has a lot going on, and so I've broken it out into three sections (thus the three images below). The list of capabilities shown here includes:
These should be fairly self-explanatory. You can see buttons to review, merge, delete, and map ingredients.
The two quicksearches are Ing. Quick Search and Nutrition Quick Search. These tools help find duplicate ingredients (I try my best to normalize ingredients) as well as to quickly search USDA nutritional data.
The basic ingredient info allows an editor to set/change:
You can also see the paginated list of recipes that contain this ingredient, a list of measures that are used across the site for this ingredient, and any substitutions that have been made.
There are two sets of similar ingredients, one administrative in nature and one public-facing. The admin-specific matching is looser (so the list tends to be longer). This list is used to help keep the ingredient set normalized.
You can see the set of classification checkboxes for each ingredient. These allow classifying ingredients based on diet and allergens. There's an additional tool that allows me to keep these consistent (it's called the Multi-Edit Tool). These can be tricky to determine because there can be quite a bit on controversy as to whether a given ingredient is considered to be paleo or not.
You can also see the existing conversions, as well as conversions for similar ingredients. These come in handy for ingredients like cheese and pasta, where it's important to keep the conversions consistent.
This editor is only used when I can't find the nutritional data for a given ingredient. E.g.: fenugreek seeds were tricky.
Sometimes, the best data comes directly from a product, and so this editor is where that data is entered into the system and then mapped to it's foodious ingredient. Other times, it comes from another country, so this tool is also used for that data.
If you want to see the entire ingredient editor as a single image, here's a link to a screen capture of garlic in the editor.