In the bowl of an electric mixer, combine the plantains and the next 8 ingredients (onion - black pepper). Beat on high speed for 30 seconds until well blended (or can mix in a bowl by hand using a wooden spoon), then gradually add the masa harina (about 1/2 cup) until the mixture forms a stiff batter. Spread the remaining masa harina on a plate.

Step 2

With slightly wet hands, form the batter into 1 1/2-inch balls. Roll the balls in the masa and flatten each ball into a 2-inch circle.

Step 3

Meanwhile, heat the oil in a large cast iron or heavy bottomed skillet pan over medium-high heat. When the oil is sizzling hot, add cakes, working in batches as necessary to avoid crowding the pan. Fry until deep golden brown on both sides, 1 - 2 minutes per side, and transfer to paper towels to drain. Sprinkle with additional salt, and allow the cakes to stand for at least 5 minutes before serving. Serve with sour cream.