As for the meatballs, I used Marina Beef Balls.
For the first step, fry the meatballs in a pan with 2 tablespoon of cooking oil. On medium heat, toss the meatballs occasionally until they are golden brown (for about 5 minutes). Put them aside.
For the sauce part, prepare the beef stock by dissolving half beef cube with 200ml of boiling water. In a pan, melt 3 tablespoon of butter, add 3 tablespoon of all purpose flour and stir them continuously until the flour turns brown. Cook until the roux begins to turn light brown.
After that, add the beef stock and 1/4 cup of whipping cream and let it simmer and keep stirring. Add some black pepper and taste first if you need to add salt. I usually don't add salt cause the saltiness from the beef stock alone is enough. The sauce is ready.
An ideal serving is 8 to 10 meatballs per plate, arrange them with fries, pour the sauce onto the meatballs, and scoop few spoonful of some strawberry jam (it would be nice if you have lingon berry). I personally add some mustard cause I love to balance the taste. Enjoy!
My reference is from here : http://dairimama.blogspot.com/2010/10/blackout-meatball.html