# ISO help making au gratin potatoes



## inchrisin (Jun 14, 2014)

I tried to make homemade au gratin potatoes for the first time last week.  I used my food processor to slice the potatoes with great success.  My roux came out runny, but was still tasty.  I snuck a little horseradish into the mix.   

My biggest issue was that the potatoes turned brown and oxidized.  I tried to make sure that the roux covered them up and then added cheese in layers to try to keep the potatoes covered.  Unfortunately, about half of them still turned brown. 

Any tips to prevent the potatoes from turning?  I've heard that vinegar can help cut pectin oxidation.  I'm worried that just soaking the cut potatoes in water will make the roux even runnier.


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## Andy M. (Jun 14, 2014)

Was there a time delay between slicing the potatoes and assembling/baking the dish?


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## ShellyCooks (Jun 15, 2014)

I agree with Andy.  Slice the potatoes just before you are ready to assemble the casserole.  Have everything ready to go and then slice the potatoes.  While slicing the potatoes, I have put the slices into lemon water to keep them from turning dark.  Then I dry them on paper towels before layering them in the casserole.  A friend of mine parboils the potatoes, cools them, and then slices them.  This cuts down on cooking time. If your sauce is runny, gradually add a little more thickener until the sauce is to your desire.  Good Luck!  Let us know how your next try turns out.


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## inchrisin (Jun 15, 2014)

I sliced the potatoes and within a minute or two I assembled the dish.  I had this on the front of my mind to try to make sure that the browning didn't happen.  Alas.


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## Kayelle (Jun 15, 2014)

You'll never have that problem with this. Just add more cheese if you wish.Here's my recipe for 

Perfect Scalloped Potatoes

3 pounds potatoes, peeled, and sliced very thin  ( I use my mandolin)
3 cups milk  
1 clove garlic  
3 tablespoons unsalted butter, softened  
Coarse salt and freshly ground black pepper  
1 cup heavy cream  
5 ounces Gruyere cheese, grated  
1.     Preheat oven to 325 degrees with a rack set in the lower third of  oven.  Combine sliced potatoes and milk in a large saucepan over high  heat.  Bring to a boil, and immediately reduce heat to low; cover and  simmer  until potatoes are just tender, about 3 minutes.  
2.    Place a  colander over a large bowl and drain potatoes, reserving  milk. You  should have 2 cups of thick, starchy milk. If potatoes have  absorbed  more than 1 cup of milk, add enough milk to bring the reserved  milk  volume to 2 cups.  
3.    Rub a 3 1/2-quart oval baking dish with garlic  and butter.  Arrange sliced potatoes in the baking dish; season with  salt and  pepper. Dot with remaining butter and pour over reserved  cooking milk  and cream. Sprinkle cheese over top.  
4.    Transfer  baking dish to oven and bake until cheese becomes deep  golden brown and  milk has reduced and thickened, 80 min approx


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## Sir_Loin_of_Beef (Jun 15, 2014)

Try keeping the sliced potatoes in a bowl of cold water until it's time to assemble the ingredients.


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## Zhizara (Jun 15, 2014)

I learned to boil my potato slices first.  I use red or Yukon gold potatoes because they will hold their shape, and I boil them so I no longer have to worry about burning the cheese while trying to get the potatoes cooked.


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## Dawgluver (Jun 15, 2014)

I boil mine first as well.  They don't have to be totally cooked.


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## medtran49 (Jun 18, 2014)

I usually just grate the cheese, then slice potatoes and layer them as I slice with cheese, S&P and dots of butter. Then, when the pot is full I add cold milk to just below the level of the top layer of potatoes and cover. If I'm in a hurry, I'll put them in the microwave for about 5-10 minutes (depending on how much in a hurry I am) then transfer to oven and let bake at 375 covered until they are almost done, then I'll uncover and top with cheese and let finish. This makes really soft, cheesy potatoes with just a very slight sauce as most of the the milk absorbs into the potatoes. If I only bake them it's takes an 1 to 1-1/2 hours depending on how much I'm making and if I nuke them it cuts down time to about half of that. They never turn brown except for a slight amount of browning around the outside edges where they are in contact with the dish.

Oh, BTW if you nuke them you have to either have them in a really big microwave-safe dish or watch carefully because the milk will boil over when it gets hot.


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