Winter's cold (in the Southern Hemisphere) and sausages are on special offer in the local supermarket. Taken together, those facts mean that it must be time for a warming, filling sausage casserole.
This dish tastes different every time it's made, due to the inclusion of the final dregs from whatever bottles of sauce have been emptied recently. When a sauce bottle is emptied, there is always a teaspoon or so adhering to the inside: it can't be shaken out onto a meal, but can be rinsed out with a small amount of hot water so that you can get all the benefit of that delicious spicy, tomato-y, chillie-y, H-P-y goodness.
As well as this 'Ible, the recipe is attached as an ODT file which can be opened in LibreOffice, or even in Microsoft Word should your tastes run that way.
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Step 1: Ingredients
The ingredients are all marked in the photograph above. The pile of sausages is way more than needed, but I cooked all of them off anyway and used the extras for another dish.
2lb sausages (1kg)
2 tablespoon oil
1/4 cup plain white flour
1 cup stock or water
1 cup of very hot water from the kettle
2 tablespoons Worcestershire sauce 
1/4 cup tomato sauce or ketchup
Whatever empty sauce bottles are lying around
 You could try using a 50:50 mixture of dark soy sauce and fish sauce.
N.B. As detailed in "Pinkeye," Worcestershire sauce must not be used as embalming fluid as zombies may result.
Step 2: Part-Cook the Sausages
To part-cook the sausages, I did actually use the oven, but that was because I needed it for another thing. If I were making just the stove-top casserole then I might fry or grill (broil) the sausages until they were half-cooked and browned on one side.
Pre-heat the oven to 200C (390F)
Cook the sausages for ten minutes, until they are half-cooked and browned on one side.
While that is happening, get the gravy done.
Step 3: Fry and Dry the Onions
Peel and half the onions, then chop into thin slices.
Heat the oil in a large saucepan.
Fry the onions in the pan until they are softened and just starting to go brown.
Turn the heat down to medium, add the flour and stir vigorously until the flour is adsorbed onto the onions.
Step 4: Adding the Liquids
Add the cup of stock or water gradually, stirring vigorously. If the stock is frozen, then just chuck the lump in and allow the gradual melting to equate to a gradual addition of liquid.
Once the stock and flour has formed a creamy, sticky mess around the onions, tip in the Worcestershire sauce and tomato sauce, stirring to mix.
Take each empty sauce bottle in turn (including any emptied getting the tomato or Worcestershire sauce) and pour a little very hot water into it. Carefully swirl it around to get all that lovely sauce-y goodness and add that to the saucepan.
If you don't have any empty sauce bottles to rinse out, then just chuck the extra water straight in.
Step 5: Simmer and Serve
Once the gravy is ready to receive them, take the part-cooked sausages, chop then into thirds and add to the saucepan.
Stir to make sure that everything is covered with everything else, adding a little water if need be.
Bring to a low simmer, then cover with a tight-fitting lid and leave on a low heat for twenty minutes to cook.
Serve with mashed potatoes and roast and steamed vegetables, or whatever else will add to the winter-warming nature of the meal.