Found on Martha Stewart's Website

3 TB Butter, melted

1 TB Olive Oil

3 Garlic Cloves, minced

1 1/2 tsp dried Rosemary, crumbled

Coarse Salt and freshly ground Black Pepper

2 small Red Onions, halved and cut lengthwise into 1/2" slices (about 2 cups)

2 Pork Tenderloins (3/4 to 1 LB each)

2 tsp All-purpose Flour

1/4 cup Madeira

Preheat oven to 450 F.  In a small bowl, stir together 1 TB butter, oil, garlic, Rosemary, 1 tsp salt and 1/4 tsp pepper.  In a small, shallow roasting pan, toss onions with half the butter mixture' push to asides' place pork in center.  Rub remaining butter mixture over pork.  Roast 10 minutes.  Heat broiler' set rack 4" from heat.  Broil until pork registers 155 F on an instant-read thermometer, 10 minutes.  Remove pork from pan.  Whisk flour and remaining 2 TB butter Ina small bowl' set aside.  Place roasting pan with onion over medium-high heat.  Add 3/4 cup water' bring to a boil, stirring to loosen any browned bits.  Add Madeira and flour mixture.  Cook sauce, stirring, until slightly thickened, 3 to 5 minutes.  Slice pork 1/4" thick and divide among plates spoon sauce on tops.