This onion glass actually tastes like onion soup in a crispy form. The sheets are translucent with a deep golden brown hue. They can be broken into pieces and scattered in a salad. They are wonderful flavor accents on hors d’oeuvres. We like to break them up and use them as a final garnish on braised meats, where they start out crunchy and slowly dissolve back into rich bites of onion syrup. Last, well, we enjoy snacking on them just as they are.
Adapted from "Ideas in Food" by Aki Kamozawa and H. Alexander Talbot
Combine the onions, glucose, water, agave nectar, and salt in a pot and bring to a boil over high heat. Reduce the heat to medium and simmer the mixture until almost dry, about 20 minutes. Transfer to a blender and puree until silky smooth. Strain into a metal bowl and cool in an ice bath. Refrigerate for at least 30 minutes.
Spray twelve 2-by-6-inch acetate sheets or foil strips with cooking spray and wipe them lightly with a paper towel to remove any excess. Use an offset spatula to spread the onion base as thinly and smoothly as possible on the strips of acetate or foil. Place them in a dehydrator and dry for 1 hour. The onion should be completely dry and come off the acetate cleanly with only a little help from an offset spatula. If it is not ready, continue drying until it reaches this stage.
Alternatively, set your oven to the lowest possible temperature and let the sheets dry out for at least 2 hours until the desired texture is reached. Let the onion glass cool before storing in a lidded container or zip-top bag with parchment paper between the pieces. The onion glass can be used whole or broken into shards, as you prefer.