This tuna tartare is easy to make and makes for an impressive first course for a dinner party. With a flavorful layer of tuna marinated in olive oil, soy sauce and chives, a layer of creamy avocado, and a magical gelée made with with yuzu infused dashi, it's as visually stunning as it is orally stimulating.
The gelée has just enough gelatin to thicken the dashi into a sauce that will stay put. When you take a bite, the heat of your mouth instantly melts the dashi turning it into a pool of flavor with a vibrant flourish of yuzu and smoky umami from the dashi.
Despite looking complicated, the preparation is fairly simple. The keys to being successful are the quality of your dashi and the fish. Dashi, is the generic word for "stock" in Japanese, but unless it's preceded by a qualifier (like chicken, shiitake, etc), it usually refers to a stock made with a combination of kombu (kelp) and katsuobushi (dried bonito). While there are several ways to make dashi, I prefer using "dashi packs" which have the ingredients ground up and sealed into little tea bags. It strikes a good balance between convenience and quality. See this post for more info on the different types of dashi.
As for the fish, it doesn't have to be tuna, you could substitute red sea bream (tai), halibut (hirame), white trevally (shima-aji), or other lean fish that's been handled and prepared to be eaten raw. One thing that I want to make clear is that just because a fish is fresh, does not mean it's safe to eat raw. In many cases (like salmon) the fish naturally contains parasites that need to be killed by freezing it at -31 degrees F for a day (most home freezers won't go below -10 F). In other cases, if the fish is not properly handled (e.g. it's cut on a cutting board used for non-sashimi-grade seafood) it can be cross-contaminated.
Unfortunately there's no clear-cut way to know for sure your fish is safe to eat raw. Terms like "sushi-grade" or "sashimi-grade" are not regulated by the FDA and so just because it carries the label doesn't necessarily mean it's safe. Personally, I would never eat "sashimi-grade" fish from a supermarket(even an upscale one) raw, unless they have clear processes in place for sourcing and handling fish meant to be eaten raw (like at most Japanese supermarkets). The bottom line is to know your fish monger well enough that you trust that they know what they are doing.
- In a small saucepan, bring the dashi to a boil, then add the salt, soy sauce, and sugar, stirring until dissolved.
- Remove the pan from the heat and sprinkle on the gelatin. Stir until the gelatin is dissolved. Stir in the yuzu juice, then pour the mixture into a container and refrigerate until set.
- Slice the tuna into strips, and then cut them into 1/2" cubes. Add it to a bowl along with the olive oil, chives, sesame seeds and soy sauce. Stir to combine. Cover and refrigerate until your gelée is set.
- When your ready to serve, cut the avocado into cubes and sprinkle with the lemon juice and a little salt. Toss to distribute evenly.
- To construct your tartare, oil a ring mold and place it in the center of a plate. Add a layer of tuna and gently pack it down.
- Add a thin layer of avocado, gently packing, and then top by scooping the gelée on top like a sauce. Give the mold a few twists to make sure it's not sticking and then lift it straight up.