In a heavy skillet, over medium-low heat, melt 2 Tbsp of butter and sauté the onion and mushrooms until the onion is translucent.
Stir in the lemon rind, bread crumbs, parsley, 1 tsp salt, and 1/4 tsp pepper.
When the parsley has wilted, (about 1 minute after you add it to the skillet) - quickly stir in the eggs to bind the mixture and remove skillet from the heat at once. Set aside.
With a rolling pin or a wooden mallet, flatten the beef pieces until each is very thin and (about twice its original size).
As you finish each piece, season it with a little salt, pepper, and a pinch of thyme.
At the widest end of each beef slice, place 1 tsp of bread-crumb mixture from the skillet.
Roll up the meat, sausage-shape, and secure it with a wooden toothpick through the center.
Roll each piece in flour. In a very large skillet, over medium- high heat, melt 4 Tbsp of butter and brown the pieces of beef.
As you finish, place them in the slow-cooker.
Pour the water into the skillet; scrape up the pan juices and turn the sauce into the cooker. Cover and cook on Low for about 5 hours.
Servings: 4 to 6