Hi, black-red sushi mushroom identify ?

Hi, i had a veg sushi a while back, n it was oh god mmhmm. It was a black-red mushroom, even more black cuz I’d suspect it was cooked in soya sauce or a similar syrup for a while.

Does anyone know what mushroom that was ? I wanna make it myself. It looks sorta like this (image attached).

I’ve had those mushrooms(?) I’m ramen to as slightly long strings n it was an incredible, umami°,
ramen.