In a large bowl, combine the green and yellow plantains, onion powder, cumin, 1 teaspoon salt and 1/4 teaspoon pepper.
Fill a large skillet with enough oil to reach a depth of inch and heat over medium heat until rippling. Working in batches, add heaping tablespoons of the plantain mixture, pressing each one with a spoon to flatten. Fry, turning once, until golden-brown and crisp, about 5 minutes. Using a metal spatula, transfer to paper towels to drain; sprinkle with salt. Serve warm.
