Cavolo Nero has a rather fibrous central spine which is best removed and used for a stock as it's full of flavour
tear away the soft leaves from the central stalk with your hands. If you prefer you can use a sharp knife. Wash the leaves and chop them into large pieces
cook the cavolo nero in a little water until just tender but still firm and bright in colour (3-5 mins). Cover the pan while cooking to keep in the steam.
chop the garlic and spring onions and saute in some good olive oil on a gentle heat until softened. Add the cavolo nero and saute for a few minutes
if you want to use the caraway toast the whole seeds in a skillet until they give off their aroma. Grind in a mortar and pestle and add to the pan
make sure there's plenty of oil in the pan, If you'e not sure, add a little more and heat it to just short of smoking
whisk the eggs and add them to the pan at fairly high heat until they cook underneath. Free the base of the tortilla from the pan with a wooden spatula. You can afford to break it up a bit at this stage
shake the pan until the tortilla slides freely. Now turn the heat to medium-low and cover with a lid to allow the eggs to cook for a couple of minutes. Check the underside with a spatula. When it's nicely browned turn the tortilla over:
place a plate over the tortilla, place your hand over the plate and flip over. Now slide the tortilla back into the pan for another 2-3 minutes. If the eggs are very fresh you can make the tortilla a little runny and thus moist
slide onto a serving plate and eat hot or cold