Cut the frozen yellowtail into block-shaped pieces, blanch them in boiling water for about 10 seconds, and then transfer them to cold water. Wipe dry with kitchen paper and cut into approximately 1cm (0.4 inches) wide pieces.
Remove the skin and seed from the avocado, then cut it into bite-sized pieces.
Slice the red onion thinly to cut across the fibers, soak it in water for 5-10 minutes, and drain to remove excess moisture.
Tear the leaves of the dill, excluding the stem.
In a bowl, mix the dressing ingredients together. Then toss the prepared yellow tail, avocado, and onion, along with mozzarella cheese, with the dressing to lightly coat them.
Plate it, sprinkle with black pepper, and garnish with lemon slices cut into wedges.
