To make the tortilla disks, take a round pastry cutter and cut out small 2-inch disks from the flour tortillas. Heat a large skillet over medium heat, add the canola oil. When the oil is hot, add the tortilla disks, turning quickly until golden brown. Remove to paper towels and allow to cool.
To make the tuna tartar: In a medium bowl, mix all the other ingredients together, except the cilantro, and allow to marinate 5 minutes before you serve. Place in the refrigerator until ready to serve.
To finish, strain the excess liquid from the tuna mixture. Place a little of the tuna mixture on top of each tortilla disk, garnish with cilantro leaves and serve on a platter.
If you want to make a special addition, add ripened diced avocado and drizzle with sour cream.