Cut the tomato into small cubes and remove the stem. In a bowl, mix the tomato, shiso leaves (torn into pieces), and sauce ingredients. Refrigerate to let the flavors meld.

Place the chicken breast vertically and use your thumb to split it along the fibers, opening it into a thinner piece.

In a plastic bag, combine chicken, salt, pepper, sake, and grated garlic. Massage until the liquid is absorbed. Add potato starch and shake to coat evenly.

Heat olive oil in a pan over medium heat. Place the chicken skin-side down and cook for 2 minutes until golden. Flip and cook for another 2 minutes, repeating until fully cooked.