Salsa Gratin Potatoes

Potatoes.  One of the cheapest foods in stores.  I buy 10 lbs for less than 2 bucks!  Now what to do with these potatoes becomes the issue.  I decided to try my hand at some fresh au gratin potatoes to accompany my bbq chicken.  But instead of it being just plain ol' au gratin, I put my own twist on it.  As usual, I encourage you to play with it, add ingredients to your liking.

Salsa Gratin Potatoes
*serves 2-3

3 Russet Potatoes (peeled and sliced using a mandoline or cut by hand 1/4 inch thick)
1/4 Onion (diced)
1/3 C. Salsa (I use a liquid or pureed salsa rather than a chunky one)
1 1/2 Tbsp. Butter (not margarine!)
1 1/2 Tbsp. Flour
1 1/4 C. Milk
1 1/2 C. Cheese (shredded, and your favorite kind)
Salt, Pepper, Garlic Powder

1. Slice your potatoes and soak in water for 15 mins.  Preheat oven to 400 degrees.
2. Put butter into a pan on med-high heat and melt.  Add the flour and whisk until the lumps are gone.  Slowly add the milk (only 1 cup, save the rest for later).  Make sure you're still whisking to keep the lumps out.  Then turn the burner down to just below med-low.  Dump in the cheese and again keep whisking. (Does your arm hurt yet?  Mine did!)  You want to keep stirring until it turns into a creamy sauce.  If it seems a bit thick, add a tiny bit of milk at a time from the last 1/4 C.
3. Take a 6x9 pan and rub the inside with butter.
4. Pour our the water and dry the potatoes a bit with a kitchen towel.  Make your first layer (10-14 slices).  Season with salt, pepper, and garlic (be generous with the salt).  Then pour a 1/3 of your cheese sauce over the potatoes.  This part doesn't need to be perfect.  Sprinkle half the onions on top of the cheese.  Then drizzle 1/3 of the salsa over the cheese.
5. Repeat a second time.
6. Use the last of your potatoes for the top layer.  Scrape the cheese into the pan covering as much as you can and then the last 1/3 of the salsa.
7. Cover with tinfoil and cook for 90 mins.
6. Uncover for the last 25 mins to get a nice browned surface.