Mix the flours, salt, sugar, and turmeric (if using) together. Add enough water to make a medium thick batter. Mix well so that it is lump free. Sprinkle the powdered cardamom on top and mix in.
Peel and slice the plantains into about ¼ inch thick pieces.
Heat enough oil in a thick bottomed frying pan to deep fry the fritters (at least 1-inch depth of oil). When it is hot (around 350F) add a drop of batter to the oil. If it sizzles and floats to top the oil is hot enough. If it burns, turn off the heat and let the oil cool a little before proceeding. If it stays at the bottom wait for the oil to heat up a little more.
Dip the sliced plantains in the batter. Let the excess batter drain from the pieces and drop the pieces into the hot oil. Keep the heat at medium. As the edges turn crisp flip the fritter and fry until the fritters are golden on both sides. Remove using a slotted spoon and drain on kitchen towels.
Repeat with the remaining pieces.
Best served warm.