Ahi Tuna with Soy Ginger Lime Sauce

Ingredients

For 4 servings

• 1/2 cup rice wine vinegar
• 1/2 cup water
• 1/3 cup sugar
• 1 1/2 teaspoons kosher salt
• 1/2 teaspoon red chili flakes
• 2 6-inch Japanese cucumbers (cut into ⅛" slices)
• 6 tablespoons lime juice
• ¼ cup soy sauce (plus 2 teaspoons)
• 2 tablespoons honey
• 2 teaspoons water
• 2 teaspoons minced ginger
• 1 teaspoon sesame oil
• 1/2 teaspoon red chili flakes
• 20 ounces ahi tuna (four 5-oz pieces, about 1" thick)
• ½ cup sesame seeds (white, black or a mixture)
• 2 tablespoons vegetable oil (or grapeseed oil)