Togarashi Tuna Burgers with Wasabi Avocado Aioli and Namasu

Ingredients

1 small Japanese cucumber, partially peeled and thinly sliced
2-1/2 teaspoons kosher salt – divided
1/2 cup unseasoned rice vinegar
1/4 cup + 1/4 teaspoon sugar – divided
3 teaspoons minced fresh ginger – divided 
1 ripe California Hass avocado
1 lemon – divided (2 teaspoons juice and 1 teaspoon zest)
1 teaspoon wasabi paste
2 pounds boneless, skinless yellowfin tuna, finely chopped
1/2 cup panko (Japanese bread crumbs)
1 egg, lightly beaten
1/3 cup chopped green onion
2 teaspoons minced garlic
1 generous tablespoon Asian sesame oil
1 tablespoon togarashi (Japanese 7-spice seasoning)
Vegetable oil, for brushing grill rack
4 sesame seed rolls, split

Instructions

Preheat grill to medium hot. For Namasu: Sprinkle cucumbers with 1/2 teaspoon salt and let stand, covered, 15 minutes. In small bowl, whisk together vinegar, 1/4 cup sugar and 1 teaspoon ginger until sugar is dissolved. Add cucumbers. Chill until needed. (Remove from liquid before serving.) For Wasabi Avocado Aioli: In small bowl, mash avocado with 2 teaspoons lemon juice. Add wasabi paste and 1/4 teaspoon sugar. Chill until needed. For Burgers: Combine tuna, panko, egg, green onions, garlic, sesame oil, togarashi and remaning 2 teaspoons ginger, 1 teaspoon lemon zest, and 2 teaspoons salt in large bowl. Handling the tuna as little possible to avoid compacting it, mix well. Divide the mixture into 6 equal patties. When the grill is ready, brush the grill rack with vegetable oil. Place the patties on the rack, cover, and cook, turning once, just until opaque throughout, about 4 minutes per side. During last few minutes of cooking, place rolls, cut sides down, on the outer edges of the rack to toast lightly. Spread cut sides of rolls with Wasabi Avocado Aioli. On roll bottoms place a patty and an equal portion of the Namasu. Cover with roll tops and serve. Serves 6