fruit grown in congo

This is a fruit I saw (and tasted) growing wild in the DRC (Democratic Republic of Congo) in January 2014 growing on trees about 20 foot high and sold in markets. Local people boil it gently and then holding with one hand and placing in lips suck out the flesh which has a strange taste sort of potato-cum pepper. The area I was in was near Kinshasa. What would it be called?
In the local Lingala language I think they said it was 'Fazoo' - but I may be incorrect.