Cut open, purple “threads” visible.
This is a very large taro root. Apparently, smaller tubers are preferable, but there are many different kinds.
Taro on Wikipedia:
This Serious Eats article finds that in the US it’s seen as an Asian ingredient:
Much of the world’s population eats taro in one way or another, so there’s nothing inherently Asian about this week’s ingredient. But here in the U.S., more likely than not, we find taro in an Asian preparation because we don’t always have wide access to African cookery or those of the Oceanic and South American cultures that also use the root.
There are many varieties of taro, the root of a perennial plant with large, elephantine leaves. Some are small, round, and hairy, like rodents, others are larger and elongated, like daikon. Inside, the flesh ranges pure white to ivory with streaks of pale purple.
Some research finds a handful of recipes.
Japanese Simmered Taro - SATOIMO NO NIMONO
This is the one recommended by Fernando.
Taro Cake Dim Sum Style
Taro Buns Vietnamese Style - Banh Mi Ngot Nhan Khoai Mon
Also various paleo recipes, like taro chips - toss with oil and salt and cook for 30min at 450F.