To thaw the tuna, remove the fish from any packing and run it under cold tap water.
Next, create a saline solution by combining salt and cold water-- about 1 tbsp of salt per cup of water. Whisk until the salt is fully dissolved. Submerge the fish in the cold salty water and let it sit for exactly five minutes. This will help set both the color and flavor of the tuna.
Lastly, wrap the tuna in paper towels and place it in an airtight container in the refrigerator until thawed. This usually takes between 5-6 hours per 4 oz of tuna.
Make the Ponzu Dressing
In a small bowl, whisk together the ingredients. Set aside until ready to use.
Assemble the Salad
When the tuna is almost thawed (still very firm and cold to the touch), slice it thinly agaist the grain.
Divide the ingredients between two plates. Lightly dress with ponzu dressing. Add sesame seeds to taste. Serve immediately.
Notes
Check out the full post for safety tips and how to pick sushi grade tuna.