These savory bites are healthier than the traditional version and my Colombian friend says they are every bit as tasty.
Slit the tips of the plantains on both ends. Then wrap them in wet paper or clean cloth towels and microwave on high for about 4-5 minutes. Then let them rest, still wrapped for another 5 minutes. Once they are cool enough to handle, unwrap the plantains.
Pull them out of their skins, and slice them into rounds about 1/2-inch thick. A few at a time, place the pieces between two cutting boards (or use a clean mallet) and smash them into thin slices. Then lightly salt them.
Heat the oil in a large, heavy pan until it is quite hot but not smoking. Add about half of the plantain slices, lower the heat, and cook them for 4 minutes, turning halfway through. They should be lightly browned when done. Drain on paper towels
While still warm, add whatever toppings you are using (hogao, ropa vieja, gauamole, etc.) or set out patacones and toppings for everyone to put on the patacones/plantains themselves.
Heat the oil in a small, heavy saucepan. Then add the diced onion, lower the light and cook for about 5 minutes until the onions is quite soft and translucent.
Add the tomato, salt and seasoning. Continue cooking until the onions and tomato are basically indistinguishable.