4 tablespoons extra virgin olive oil
4 tablespoons butter
1 yellow onion, medium and sliced
thin
Salt to taste
Black pepper to taste
1/2 cup dry white wine
3 fresh rosemary sprigs, finely chopped
1/2 cup Marsala wine
1/2 cup beef broth
2 tablespoons balsamic vinegar
4 beef tenderloin filets (6 oz each)
parsley, finely chopped
Rosemary sprig, for garnish
Heat oil and butter in large saute pan over medium
heat. Add sliced
onions, salt, and pepper. Cook 10 minutes or until
caramelized
(softened and golden brown), stirring frequently.
Add wine, broth,
vinegar and chopped rosemary. Bring to a boil.
Reduce heat and simmer
for 10-15 minutes or until sauce is reduced by
half.
Rub beef filets with oil, then season with salt
and pepper. Grill to
preferred temperature. Place grilled filets on
a large platter; top
with sauce. Garnish with parsley and rosemary.