For the tuna tartare, Crudo E Nudo chef and owner Brian Bornemann uses shrimp broth, confit onion, and white soy sauce, which give it a rich umami flavor. You can make the broth and confit in advance. The tartare covers slices of toasted bread and is garnished with aromatic yuzu oil, black sesame and scallions. This is not just any toast.
You will have more candied onion left than you need for this recipe. Reserve the confit for another use in a covered container in the refrigerator for up to 2 months.
Note: Bornemann uses O-Med yuzu olive oil, available at Surfas and other specialized markets and online. Alternatively, you can mix 1 tablespoon of good olive oil with ¼ teaspoon of yuzu juice. White soy sauce is available in select Japanese and specialty markets and online.