Empty the spinach into a colander and run water over it just to get it wet. Heat the oil in a large, heavy-bottomed pan. Add the onion and saute it until it begins to turn golden brown around the edges. Sprinkle on the Goya seasoning. Dump the spinach leaves into the pan, sprinkle on just a tiny bit more water, then place the lid on the pan. Let the spinach cook down for about 5-6 minutes, until it is a beautiful bright green. Serve with anything and everything.