Step 1

Add all ingredients (except for the watermelon) to a small mixing bowl and stir until well combined. Place the watermelon steaks and marinade in a container, making sure the steaks are entirely submerged/coated in the marinade.

Step 2

Marinate them in the refrigerator for 24 hours.

Step 3

Preheat the oven to 275 degrees Fahrenheit.

Step 4

Line a large sheet pan with a piece of parchment paper.

Step 5

Drain and shake off the excess marinade from the watermelon. I like to also lightly dab the watermelon with a piece of paper towel to prevent the marinade from burning in the oven. Then, place them on the prepared baking sheet.

Step 6

Bake them on the middle oven rack for 1 hour, flipping them halfway through.

Step 7

Allow the watermelon tuna steaks to completely cool down at room temperature before assembling the burgers.

Step 8

Add all ingredients (except for the coleslaw veggies) to a mixing bowl and whisk until well combined. Then, toss in the veggies and stir until evenly combined.

Step 9

Let the slaw marinate for 20 minutes.

Step 10

Add the wasabi powder and water to a small bowl and stir until a paste has formed. Let this rest for 5 minutes to activate the flavor.

Step 11

Add the mayonnaise and stir until evenly combined.

Step 12

Lightly toast a bun. Spread roughly one tablespoon of wasabi mayo on both slices. Top the bottom bun with half of the Asian slaw, followed by one watermelon tuna steak, 1/4 of a thinly sliced avocado seasoned with a tiny pinch of salt, one to two tablespoons sushi ginger, and finish with the top bun!