Prepare Egg "Rice": Whisk egg yolks with half of the sea salt until well combined. Pour into a greased slow cooker insert or a suitable dish that fits inside your slow cooker for a water bath method. Cook on low for 1-2 hours, or until the mixture is firm and slightly bouncy to the touch. Once cooked, crumble the egg yolk mixture to resemble rice texture.

Assemble Sushi Rolls: Lay out a piece of cling film on a clean surface. Place a thin layer of the crumbled egg yolk "rice" on the cling film, then add a layer of thinly sliced fish on top. Using the cling film, roll tightly into a sushi roll shape. Repeat until all ingredients are used.

Cook in Slow Cooker: Place the sushi rolls in the slow cooker (you may use a steamer basket if available) on low for 1-2 hours, just until the fish is tender but not overcooked. The goal is to gently warm the fish and meld the flavors without cooking the fish through like traditional sushi.

Serving: Unwrap the rolls, slice into sushi pieces.