Add all marinade ingredients to a medium mixing bowl, and whisk well to combine. Cut tuna into small cubes and toss in the marinade. Cover bowl with plastic wrap, or transfer to an airtight container. Refrigerate for at least 30 minutes and up to 1-2 hours before serving. Best if eaten eaten within 48 hours. Keep chilled. Serving suggestions: Rice bowl, cauliflower rice bowl, with wonton chips.