Watermelon "Tuna" Sashimi
Imported from Instagram
7 hoursMedium4 servings

Watermelon "Tuna" Sashimi

A clever and visually stunning vegan alternative to raw tuna. Thick watermelon slices are baked and marinated in a savory, ocean-flavored nori and soy sauce mixture to mimic the texture and taste of sashimi.

Mise turned a cooking video on Instagram into this written step-by-step recipe — 9 ingredients, 6 steps, 7 hours, with a generated photo for every step.

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Time420min
LevelMedium
Servings4
Method 6 steps
01

Place the nori sheets, sesame oil, soy sauce, vegan fish sauce, neutral oil, and water in a blender and blend until well combined to create the marinade.

02

Remove the rind from the watermelon and slice the flesh into 'steaks' approximately 4 cm thick.

03

Brush the watermelon steaks generously with the marinade and bake at 180°C (350°F) for 1.5 to 2 hours, turning them occasionally.

04

Remove the steaks from the oven and submerge them in the remaining marinade. Let them cool and marinate for at least 5 hours so the flavors penetrate deeply.

05

Optional: Pour any remaining marinade into a saucepan, bring to a boil, and reduce over medium heat until it becomes a syrupy glaze.

06

Slice the marinated watermelon into thin sashimi-like pieces or cubes. Drizzle with the reduced glaze, and garnish with chopped scallions and sesame seeds before serving.

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Notes

Transforming fruit into a savory seafood alternative relies on long, slow roasting to break down the cellular structure of the watermelon. This process removes excess moisture and collapses the flesh, resulting in a dense, chewy texture that remarkably mimics raw tuna. The addition of nori and vegan fish sauce provides the necessary brine and ocean scent, while the natural sugars in the fruit caramelize to create a deep, complex base for the savory marinade. This dish works best as a centerpiece for a plant-based omakase or a light lunch when served alongside pickled ginger and wasabi.

Timing is the most critical element here. The extended baking time ensures the interior loses its grainy, watery crunch, while the subsequent five-hour soak allows the soy-based brine to permeate the core of each slice. Expect a plate that looks indistinguishable from traditional sashimi but offers a surprising balance of salty, umami, and subtle sweetness. It is a refined technique that values patience over complex knife skills.

Before you start

  • When blending the marinade, ensure the nori sheets are completely pulverized into tiny specks to prevent large, leathery pieces from sticking to the watermelon steaks.
  • The watermelon is ready to leave the oven when the exterior looks dark and slightly shrunken, feeling firm rather than soft or mushy when pressed.
  • Monitor the reduction carefully in the saucepan; the glaze turns from syrupy to burnt quickly due to the high sugar content inherent in the fruit.
  • Wait until the steaks are completely chilled before slicing into thin pieces. Warm watermelon is fragile and will tear rather than produce clean, sharp sashimi edges.

Swaps that work

  • Replace 0.75 cl vegan fish sauce with an equal amount of extra soy sauce and a pinch of salt for a similar savory depth.
  • Substitute 1.25 cl neutral oil with toasted sesame oil for a more intense, nutty aroma and a slightly richer mouthfeel in the marinade.
  • Exchange 0.25 bunch scallions for 10 grams of fresh chives to provide a more delicate, less pungent onion flavor to the garnish.

Keeping it

Store any leftovers in an airtight container in the refrigerator for up to two days. Keep the slices submerged in any remaining marinade to prevent them from drying out or losing their dense texture. This dish is intended to be served cold or at room temperature and should not be reheated, as further cooking will make the watermelon too soft. Freezing is not recommended because the ice crystals will destroy the carefully achieved tuna-like consistency.

Questions

Can I prepare this dish a day in advance?

Yes, preparing this a day ahead is actually preferred. The watermelon benefits from a long soak in the marinade, and twenty-four hours in the refrigerator allows the salt and seaweed flavors to penetrate the dense fibers more thoroughly than the minimum five-hour requirement.

Why did my watermelon come out mushy instead of firm?

Mushy texture usually results from under-baking or using a watermelon with very high water content. Ensure the oven is at the correct temperature and the steaks bake for the full duration. The goal is to evaporate enough moisture so the fibers collapse into a meaty structure.

Do I need to remove the seeds before baking?

Using a seedless mini watermelon is highly recommended for this recipe. If your fruit contains large black seeds, you must remove them during the slicing stage. Small, soft white seeds are edible and can remain, as they become unnoticeable once the watermelon has been roasted and marinated.

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