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Vegan Tuna Steak

Course: Appetizer
Cuisine: French
Keyword: Tuna Steak, Vegan
Prep Time: 25 minutes
Cook Time: 1 hour 30 minutes
Marinade: 30 minutes
Total Time: 1 hour 45 minutes
Servings: 4 people as an appetizer
Calories: 278kcal
How can watermelon be transformed into a vegan tuna steak? Our marinade brings umami and the essence of the sea. Spending an hour in the oven draws out moisture transforming the texture of the watermelon as well as intensifying the flavors. 
The surrounding flavors of the dish are building and support the vegan tuna as a whole with earthy fermented red miso paired with the rich garlic confit to add depth which pairs with lean vegan tuna steak perfectly. 
Print Recipe


Watermelon Marinade

Herb Crust

  • ¼ cup parsley fresh chopped
  • 2 Tbsp chives chopped fresh
  • 1 Tsp dill fresh chopped

Roasted Miso Garlic Sauce

Asparagus Spears with Chives

  • 10 asparagus spears
  • 1 Tbsp olive oil extra virgin
  • 1 Tbsp chives fresh chopped
  • Pinch salt kosher
  • 2 cups ice for a water bath

Lemon Zest Roasted Shiitake Mushrooms


  • ¼ cup fennel fronds


How to make the marinade for vegan tuna steak

  • Cut 2-inch thick watermelon rounds, and trim them into a large square, removing the rind. Cut a steak-shaped rectangle that is about 2 inches by 3 inches.
  • Heat the extra virgin olive oil over low heat, and add the kelp granules. Cook for 1 minute.
  • Add the poultry seasoning, granulated garlic, and mushroom powder. Continue to cook for another minute.
  • The lite soy sauce, black vinegar, red wine vinegar, marmite, and red miso. Cook for 4 minutes.
  • Place in a bowl, and allow the marinade to cool before adding the portioned watermelon steaks.
  • Marinade the watermelon steaks for 35 minutes.

How to cook Vegan Tuna Steaks

  • Preheat the oven to 350 degrees.
  • Line a baking sheet with parchment paper, placing a cooling rack on the baking tray.
  • Place the watermelon steaks on the rack, and baste the tops of the vegan tuna steaks with the marinade.
  • Cook for 30 minutes, flip the vegan tuna steaks, basting the tops. Cook for another 30 minutes.
  • Allow the vegan tuna steaks to cool for 5 minutes.

How to make Herb Crust and finish Vegan Tuna Steak

  • Pick the parsley leaves from the stems, it's best only to chop the leaves. Chop the parsley finely.
  • Slice the chives as finely as possible.
  • Mix the chives and dill into the parsley.
  • Heat a heavy sauté pan over medium-high heat.
  • Press the vegan tuna steaks into the chopped herbs. Cook both sides for 2 minutes.
  • The vegan tuna steak should rest for 5 minutes before you slice for platting.

How to make roasted miso garlic sauce

  • Remove the stems of the peeled garlic cloves.
  • Gently heat extra virgin olive oil over low heat, add red miso paste, and garlic cloves. Cook the garlic for 15-20 minutes.
  • Using a handheld emulsion blender or blender, puree the garlic until smooth and adjust the consistency with plant milk. You're looking for a thick smooth paste consistancy, not to thin.

How to make asparagus spears with chives

  • Trim about 2 inches off the bottom of the asparagus bottoms. Gently peel the asparagus starting about 2 inches from the tip. Try not to remove too much of the flesh of the asparagus.
  • Bring a pot of water to a boil, and add the kosher salt.
  • Cook the asparagus for about 2 minutes, the asparagus should be tender and firm at the same time, there should be a little texture when you bite into the asparagus spears. The asparagus should be bright green in color.
  • Place the asparagus in the ice bath for 3 minutes.
  • Gently dry the asparagus spears with a dry towel.
  • Cut the asparagus in half on the bias. If your aspsagus spears as very long, cut into 3 peices.
  • Combine the extra virgin olive oil and the chive then toss the asparagus to coat.

How to make lemon zested shiitake mushrooms

  • Remove the stems from the shiitake mushrooms.
  • Heat a heavy sauté pan over medium-high heat.
  • Place the shiitake mushrooms in the pan, making sure not to overcrowd the pan. Cook for 3-5 minutes, the mushrooms should be turning brown and a little crisp on the edges.
  • Flip the shiitake mushrooms, add the lemon zest, stir to combine and coat.

How to plate vegan tuna steak

  • Start with placing the roast garlic and miso source in the middle of the plate, in a rectangle shape. 
  • Slice the vegan tuna steak four times on the bias. Gently slide a small pastry spatula under the vegan tuna steak, or a knife will work also. Gently slide the vegan tuna steak on top of the roasted garlic miso sauce. 
  • Place the asparagus spears around the plate. Garnish the plate with dill fronds, and chive points. 
  • Drizzle the extra virgin olive oil and chive liquid around the plate. 


Nutritional values are an estimate.


Calories: 278kcal | Carbohydrates: 24g | Protein: 7g | Fat: 19g | Saturated Fat: 3g | Polyunsaturated Fat: 2g | Monounsaturated Fat: 13g | Sodium: 912mg | Potassium: 575mg | Fiber: 4g | Sugar: 5g | Vitamin A: 801IU | Vitamin C: 34mg | Calcium: 139mg | Iron: 3mg