onions and potatoes into a bowl, season, then mix them up - place a very large amount of olive oil into your pan and heat gently then add the onion and potato mix to the pan - the oil should almost cover the mixture - turn the heat down and let it cook gently for 20-30 minutes, you want the potatoes to be fall-apart-soft and not too brown at all - once the potato is cooked through take it out of the pan and allow the oil to drain off - in a large bowl, mix the eggs then tip the potato and onion mix into the eggs... at this point you can either leave the potato in this mix for a while before cooking so that the onions permeate into the eggs or you can cook directly - re heat the pan, add a little oil this time and pout the mixture in - cook gently and slowly, checking with a spatula how the underside is browning - you're looking for a gentle golden colour - the top probably won't be cooked and still a little runny - this is ok - once browned, take the pan to the sink, place a large plate over the top and quickly flip the pan transferring the tortilla to the plate....then drop the plate... no... don't... place the pan back on the heat and slide the tortilla back into the warm pan and gently cook again for a further 5 minutes or