In a microwave-safe container, combine the eggplant, white dashi, and tuna. Place the frozen udon on top. Cover loosely with plastic wrap and microwave (600W) for the cooking time indicated on the udon package plus 3 minutes, one serving at a time.
Once slightly cooled, add sesame dressing and mix thoroughly.
Plate the dish with the eggplant on top. Garnish with shredded shiso leaves.
Add grated ginger to taste if desired.
Tips
Microwave times may vary—adjust based on your appliance.
Microwaving all ingredients together steams the udon while infusing the eggplant with flavor.