In a large skillet, heat the olive oil over medium heat, and saute the onion and Soyrizo pieces.
Add the ripe plantain slices, and continue cooking for 8 minutes until the plantain slices and Soyrizo pieces are well cooked.
Transfer mixture to a colander, and drain off the oil.
Add Egg Beaters into a bowl with baking powder, and season with salt and pepper.
Stir in plantain mixture.
Melt butter in a skillet over medium heat, add the omelette mixture to the skillet and cook over medium heat for about 7 minutes.
Place a large plate over the frying pan, invert the omelette onto the plate, and slide it, uncooked side down, back into the skillet.
Cook for another 5 minutes.
Serve warm.