http://allrecipes.com/recipe/16768/puerto-rican-tostones-fried-plantains/
Peel the plantain and cut it into 1-inch chunks.
Heat the oil in a large skillet. Place the plantains in the oil and fry on both sides,; approximately 3 1/2 minutes per side.
Remove the plantains from the pan and flatten the plantains by placing a plate over the fried plantains and pressing down.
Dip the plantains in water, then return them to the hot oil and fry 1 minute on each side. Salt to taste and serve immediately.