With meat mallet or rolling pin, flatten meat to approximately a 10x8 inch rectangle. Spread mustard over meat. In large skillet, over medium high heat, cook bacon and onion until bacon is crisp; pour off fat, reserving 1/4 cup.

Spread bacon mixture over meat; sprinkle with pickle. Roll up meat from short end; secure with string. In large skillet over medium high heat, brown beef roll in reserved fat. Place in a 13x9 inch baking dish.

Stir flour into fat in skillet until smooth; gradually stir in beef broth. Cook and stir over medium heat until thickened. Pour sauce over beef roll. Cover, bake in 325 degree oven for 1 1/2 hours or until done.

Let stand 10 minutes before slicing. Skim fat from sauce; strain and serve with meat.