Dice the tuna, against grain, into 1/4-inch cubes. In a bowl combine the lemon juice, lime juice and sugar. Stir in the vinegar and whisk until incorporated. Add the diced tuna, the ginger, red onion, green onion and herbs. Allow the tuna to marinate* for up to 1 hour.
Drain the excess liquid from the tuna, scoop into cones and serve.
*The marinating of the tuna with the fresh juices and sugar will be the cooking or curing process for the tuna
Top with a tropical creme fraiche or additional green onions