First, get your tuna fillets ready. They should be sushi or sashimi-grade, meaning they are fresh enough to eat raw. If you haven’t done it already, cut the tuna into bite-sized cubes.

Next, wash your mesclun mix or baby greens thoroughly. You want them clean and crisp. Dry them using a salad spinner or paper towels. Set them aside in a large mixing bowl.

Take your onion and dice it finely. The smaller, the better, as this will enhance the flavor without overpowering the dish. Add the diced onion to the greens bowl for a crunchy texture.

Let’s make the dressing. In a separate bowl, combine rice vinegar, grapeseed oil, sesame oil, soy sauce, the filtered water, sugar, mustard powder, and optional lime juice and ginger. Whisk well until all ingredients blend smoothly.

Now, pour the dressing over the greens and onions. Toss it gently to avoid bruising the leaves. Finally, add the cubed tuna and give it a light toss. You can sprinkle some salt and pepper to taste.