Magazine Challenge: Pork Tenderloin with Rosemary

So.
J likes pork tenderloin, but few other cuts of pork.  I'm pretty sure it's because his mother cooked it to the point that it was dry, but for the most part I don't push. 
But sometimes I realize that I've bought too much pork tenderloin on sale and I need to use it up whether or J really likes it or not. 
Enter this recipe.  And the above scenario.  You know what I really liked about this recipe?  It took less than an hour, and we got a roast out of it.  So good.  especially with red onions.  Roasted red onions often taste to me like apples, and that just makes it all good.  Especially with pork. 
Easy?  Check.  Tasty?  Check.  All good.
I present to you now from September 2005 Everyday Food, Pork Tenderloin with Rosemary:

Ingredients:

3 Tbsp butter, melted
1 Tbsp olive oil
3 cloves garlic, minced
1-1/2 tsp dried rosemary, crumbled
Salt and Pepper to season
Red onion, halved and cut into strips, about 2 cups
1 lb pork tenderloin
2 tsp flour
1/4 dry sherry or Madeira

Method:
1.  Preheat oven to 450F.  In a small bowl, stir together 1 Tbsp butter, oil, garlic, rosemary, 1 tsp salt, and 1/4 tsp pepper.
2.  In a small roasting pan, toss onions with half of the butter mixture.  Push to the sides, and place pork in the centre of the pan.  Rub the remaining butter mixture over the pork.  Roast 10 minutes.
3.  Heat broiler; broil pork until it registers 155F on a thermometer.  About 10 minutes.  Remove pork from pan.
4.  Whisk flour and remaining 2 Tbsp butter together.  Place roasting pan on a burner over medium heat.  Add 3/4c water, bring to a boil, loosening any browned bits.  Add sherry and flour mixture.  Cook until slightly thickened, about 5 minutes.

From November 2005 Everyday Food. (You're going to have to trust me on this.  The recipe is nowhere to be found on the Martha Stewart website.)

Red onion, ready for roasting.  It's funny I have no process pictures of the meat.  Just the sauce.  But Frankly, the sauce was the best part.

This is what I used in the sauce.  I'm guessing cider would work as well.

This smelled so good as it cooked.  The original recipe did double the meat I did.  I made the full sauce though.  We didn't miss the extra meat.

And here is the final product.  J has told me that we can have this again.  I'm prone to agree.  It was easy and tasty.  With broccoli and mashed potatoes, it was a great fall dinner.