I make a mirepoix in the food processor, add shedloads of crushed garlic and fry it in olive oil, then transfer to a cast iron casserole
brown the mice, then chuck it on top of the mirepoix
brown chicken livers and puree them, add to the mix
add chopped tomatoes, tom puree, celery salt, black pepper, mushroom ketchup, passata if I have some, red wine, concentrated beef stock (Waitrose demi glace is my favourite, but Knorr will do).
Then my secret magic ingredient: a shake of balsamic vinegar and a teaspoon or two of black treacle (sounds weird, but gives a wonderful richness and piquancy to anything beefy).
Reduce on the stove top till the excess liquid has gone, then either leave it covered on a low heat for a couple of hours or pop it in the oven (gas mark 3) for a couple of hours.
If it's made the day before it's even better, and it freezes well.