A rolled omelette made with dashi, cooked in thin layers in a square pan until it's juicy and just set.
What makes it dashimaki tamago
Dashi in the egg.
Cooked in layers in a rectangular pan.
Rolled while still wet on top.
Where it comes from
The Kansai take on tamagoyaki: more dashi, less sugar, so the roll is softer and weeps a little when cut. Rolling layer on layer is a skill cooks practise for years.