Chop the onion, carrot, and green onion finely.

Remove excess water from the tofu and drain oil from the tuna. Mix tofu, tuna, chopped vegetables, egg yolk, salt, and potato starch in a bowl until well combined.

Shape the mixture into triangles using a triangular mold, keeping the thickness under 1cm.

Heat a pan with cooking oil and cook the triangles on both sides over low heat until fully cooked.