Wash the peas well in plenty of cold water. Place them in a pot and cover them by 2 finger widths with lukewarm water. Add the grated onion. Simmer the beans for approximately 1 hour until they are reduced and become purée. Add some salt and stir. If needed, during cooking time add some warm water. Place the bizelofava on a platter and let it cool. In a saucepan, sauté the onions cut in strips in olive oil until they are golden. Add the lemon juice. Pour it on the green fava and serve in bowls.