In a food processor, pulverize the bananas with the vanilla extract. Sift together the flour, baking powder, salt, and sugar. Add the lime zest and dry ingredients to the food processor. Mix until dough is of a light texture. Rest for a few minutes, then form the dough into 15 patties. Fry cakes in 1/2-inch-deep oil, turning to brown evenly on both sides. Drain on paper towels, sprinkle with cinnamon sugar, and serve hot with lime wedges.