Recipe that's a combination of some useful ideas I got from a post in the Aus/NZ forums along with a few ideas from recipes found on the web. If you don't have access to Vegemite try black sauce (thanks mummamills for that and more!).
Place lamb liver in a small bowl, sprinkle with sea salt, cover with water and refrigerate for a few hours.
Peel skin off lamb's fry and remove any other pieces of tissue, slice and lightly coat with the flour. I normally like to cut any long strips in half again so they're bite size.
Remove excess fat and rind from the bacon and chop coarsely. Leave a bit of streaky fat on the bacon, it adds to the flavour.
Melt butter in a frypan, add bacon and onion and fry around 8-10 minutes over medium to high temperature until onion is soft and bacon is fairly well cooked but not crisp.
Add lamb's fry and lightly fry a few minutes turning often to brown evenly, you don't need to cook it through at this stage.
Blend water, vegemite and cornflour and add to the pan and mix through well.
Bring to a gentle boil, reduce temperature to a simmer and continue to cook for 20 minutes stirring every 5 minutes or so. It may take a little more time but you want a fairly thick gravy runs a little slowly off a spoon.
Serve with mashed potatoes or it's also good re-heated and served on toast for breakfast.