WTF Is This Root?

Can anyone tell me what this vegetable is called? I've never encountered it before until a good friend of mine, Jahman brought some for the o's this week. When I saw him eating it with the homies I thought "Here we go again. Another vegeterian thing from Jahman". As a Rasta he only consumes off the herbivor menu.
He offer me a taste and I was very reluctant to try it. Jahman explained that it is a super food used often by Nigerians. Eventually I took it in my hand and removed the skin as instructed.

I dipped some salt as I was instructed and took my 1st bite. My expectation of a medicinal flavour was shattered! OMG! I couldn't wait to finish chewing so that I could take another chomp. I couldn't get enough. Fueled by the munchies after blazing some good good I wanted more of this porridge like treat.

This super root vegetable grows in Mpumalanga (my home province) and in Mozambique according to the homies. It is called Dumbe in Zulu, but I don't know what the English name is. If anyone knows please drop it in the comments section below. Your assistance is highly appreciated as I need to get my hands on more of this scrumptous crop.