In a large saucepan over medium heat, combine the plantains and stock or broth.
Simmer for 10 minutes, or until the plantains are very tender.
Drain in a strainer, reserving the cooking liquid. Leave the plantains in the strainer.
Heat the oil in the saucepan. Add the onions, garlic and bacon.
Cook for 4 minutes, or until onions are just beginning to brown.
Stir in the plantains and mash with a pestle or the back of a wooden spoon.
Add the reserved stock as necessary to obtain a thick, creamy puree. Season with salt and pepper.
Transfer to a serving bowl. Sprinkle with the chives or scallions.
