Trim the tenderloin by removing the silver skin, sinews, and membranes. 

Cut it into slices about 1.5 cm thick and lightly pound them with the palm of your hand.

Cut the bacon into cubes.

Roughly chop the onions.

Cut the root off your mushrooms and rinse them thoroughly. Dry them off and cut them in half.

Sauté bacon and onions in a roasting pan. If the bacon is fatty, there's no need to use extra fat, but if it's not so fatty, it may be necessary to add a bit of neutral-tasting oil. Remove bacon and onions when the onions are golden.

Brown the tenderloin slices for 1-2 minutes on each side in the drippings. Season with salt and pepper, and return the bacon and onions to the pan. Add about 1 dl water, mushrooms, and tomatoes.

Let everything simmer for about 15 minutes under a lid until the meat is tender.

Add the sausages to the tenderloin stew 4-5 minutes before it is done.

Thicken the sauce, and season with salt and pepper and possibly a bit of vinegar, sugar, lemon juice, or gastrique to taste.