Bring a small pot of water to boil. Add plantain with salt, cover and cook for 15 minutes.
Drain water from plantain reserving some for mashing. Add butter and a little reserved liquid and mash together until smooth. Top with pickled onions.
Meanwhile, heat cup of vegetable oil in a skillet. Add slices of salami and cook for a 2-3 minutes on each side. Remove to drain on paper towel lined dish.
Add frying cheese to oil and cook on each side for 3-4 minutes until golden brown. Remove and set aside on paper towel lined dish.
Cook egg to desired doneness.