I don't recall his mother being mentioned so far in the anime. Is there any info on her status/location?
In the fifth season of the anime, Soma's mother's name is revealed as Yukihira Tamako, and her status is deceased. She's the reason why Joichiro stopped traveling so much and came home - he had to take care of Soma and the family restaurant.
The wiki also provides some information regarding her debut in the series:
- Manga debut: chapter 311
- First mention: Episode 74
- Cameo: Episode 76
- Full appearance: Episode 83