I had never come across them until I went to Venezuela for a year. They remain one of my very favourite foodstuffs. Plantain chips are so superior to their potato equivalent!
But I don't recall having seen them quite so blackened at the markets there. It was my Cuban mother-in-law who introduced me to the delighted of deep-fried super-ripe plantain, an essential feature with every 'proper' meal. Suck sticky, caramelised but still savoury goodness!