Watermelon Tuna [sashimi + steaks]

Transform watermelon into impressive vegan watermelon tuna with just 6 ingredients and an hour of baking for cruelty-free vegan tuna steaks, sashimi, and more!

What is Vegan Watermelon Tuna?

We’ve already shared a recipe for delicious vegan tuna salad (thanks to chickpeas). However, in this recipe, ingredients like nori, soy sauce, miso, and watermelon combine refreshing, fruity watermelon into an impressive vegan watermelon tuna with a raw fish texture.

How does it work? Two things: the sauce and the baking! Baking helps to remove excess moisture from the melon, turning it from juicy and crisp to dense yet still tender with a fishy ‘floppiness.’ At that point, it definitely looks the part.

However, additionally, it’s combined with a marinade/sauce that contains flavors we typically associate with tuna (like the fishy nori) to transform the watermelon into a convincing vegan and vegetarian tuna.

It might not be an exact replica, but making vegan tuna from watermelon certainly hits the spot. Plus, there are several ways to adapt the watermelon tuna recipe. E.g., to make grilled watermelon tuna steaks or flavor-packed spicy ‘tuna’ for poke bowls, etc.

Looking for watermelon recipes that are a little more traditional? Check out our healthy and refreshing watermelon popsicles, slushies, or watermelon coolers.

The Ingredients

• Watermelon: We recommend using a seedless, slightly under-ripe or ‘just’ ripe watermelon so it isn’t overly sweet.
• Nori: Nori is the thin seaweed sheets you use for sushi and will help provide the vegan tuna sashimi with a fishy, ocean-like flavor.
• Oil: We prefer to use a neutral cooking oil, like vegetable oil or canola oil, to add more of a silky mouthfeel (like the fattiness of fish). However, some prefer to substitute a small portion of it with sesame oil for flavor depth.
• Soy sauce: Use regular or low-sodium soy sauce (or tamari/coconut aminos if you’re gluten-free) to add an umami-rich saltiness to the watermelon vegan tuna.
• Apple cider vinegar: Or rice vinegar (though that’s sweeter) to balance the melon’s natural sweetness and add a subtle tang to the watermelon sashimi recipe.
• White miso paste: While technically optional, this really helps to add an impressive amount of umami flavor with subtle salty-sweetness.

Flavor Variations & Add-ins

• Garlic: Some finely minced raw garlic adds to the savory, aromatic flavor.
• Sesame seeds: Raw or toasted to garnish the vegan tuna sashimi.
• Scallions: Finely sliced to add to the savory marinade, making it similar to tuna poke.
• Hot sauce/sriracha: Just a little if you want to make ‘spicy tuna.’ Red pepper flakes would also work to add heat.
• Ginger: Just a little minced ginger complements the flavors of ‘spicy tuna.’
• Liquid smoke: Add a few drops to make more of a ‘smoked tuna’ flavor.

How to Make Watermelon Tuna

• 1) First, preheat the oven to 375F/190C, line a baking sheet with parchment paper (or a silicone baking mat), then use your hands, kitchen scissors, or a small food processor to crumble/mince the nori.
• 2) Then, cut the watermelon in half and use a sharp knife to remove the peel.

• 3) Next, cut it in half and slice each half into 1-inch thick half-moon slices.

• 4) Combine all the sauce ingredients (oil, soy sauce, minced nori sheets, apple cider vinegar, and miso paste) in a large baking dish.

• 5) Working one at a time, dip each watermelon slice into the sauce on both sides and transfer to the prepared baking dish. Repeat with the remaining melon slices.

You can optionally pour any leftover sauce over the melon slices OR save it to pour over the melon after baking for even more flavor.

• 6) Bake the watermelon for 50-60 minutes or until it’s tender and fishlike in consistency.
• 7) Finally, allow it to cool before slicing it into 1-inch (or thinner) slices.

For Grilled Watermelon Tuna Steaks

For the best texture and flavor, we prefer to still bake the watermelon slices for 50-60 minutes, THEN marinate them in the sauce for 2-24 hours.

Then, cook the watermelon tuna steaks on a preheated grill (or grill pan) over medium heat for 2-3 minutes per side until seared with the charred grill lines.

FAQs

Pro Recipe Tips

• Use seedless watermelon: The crunchy black seeds take away the believability of the vegan tuna watermelon and need removing, so, it’s easiest to buy a seedless melon.
• Adjust the shape: We prefer to bake it as written, then slice it down to size. However, you can optionally cut it into ¾-1-inch cubes from the get-go to make vegan tuna poke bowls. Remember, it will shrink quite a bit while it bakes.
• Monitor the melon: You don’t need to keep a constant eye on it, but checking it occasionally to ensure it isn’t browning/charring is a good idea. We just want to soften and remove excess water, not fully ‘roast’ it.
• For even more flavor: You can optionally leave the watermelon to marinate in the sauce anywhere up to overnight.

Storage Instructions

Allow the watermelon tuna to cool, then store it in an airtight container in the refrigerator for up to 4 days. The longer it sits, the more the flavors meld and marinate, making it even more delicious. To serve, pour away any excess liquid, and enjoy.

How to Serve Watermelon Tuna?

• As vegan sashimi tuna
• Served over vegan sushi rice
• Draped over sushi rolls or to make watermelon tuna sushi
• In a homemade vegan poke bowl/sushi bowl

Related Recipes

• Vegan tofu ‘fish’ sticks
• Tofu sushi
• Chickpea tuna salad
• Grilled tofu steaks
• Mushroom steaks
• Buffalo cauliflower wings

Photos by Alfonso Revilla