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Why is my potato gratin watery?

(19 Posts)

I've made it a number of times, and only the first time was it ok.
Each time since, it's had masses of liquid in the botton of the dish, but I'm not doing anything different.
I use a semi-waxy potato (rather than floury, which would just fall to pieces) and milk, with a bit of cheese in between layers. Bake for an hour at 200°C. Leaving it to stand does not help.
Any ideas? Do I need to be putting some flour/cornflour in there somewhere?

bibbitybobbityCAT Fri 09-Oct-09 20:42:06

I think you are supposed to use cream rather than milk?

theyoungvisiter Fri 09-Oct-09 20:43:02

It's probably just differences in the type of potato - some are wetter than others and it changes with the seasons. Do you cover it when you bake it?

I would use double cream rather than milk if you want it thicker, or bake it for longer to burn off the liquid. Cornflour will just be yucky and sticky.

theyoungvisiter Fri 09-Oct-09 20:44:24

I always use double cream for gratin, with bits of onion and goats cheese in between the layers. Mmmmmmmmmmmm....

You can make it with milk but the effect is completely different.

SazZaVoom Fri 09-Oct-09 20:45:23

Dry the potato on some kitchen towel for a while before you put it in the dish? I do this with grated potato for potato rosti

I have used half-half milk and cream, but while it made the whole thing creamier, it didn't affect the water level.

Can someone let me know what ratio of potato to cream/milk/liquid they are using?

Thanks for the replies, btw. Wasn't expecting anything so fast!!

BecauseImWorthIt Fri 09-Oct-09 20:47:03

Definitely use cream. I, personally, would also use floury potatoes, so that they absorb some of the liquid

fishie Fri 09-Oct-09 20:49:02

nigella does something around simmering the potatoes in milk/cream and then pouring it into a buttered dish to bake. evaporation must have something to do with why it is wet as well.

Wouldn't floury potatoes break up though?
I'm following this recipe.

The taste is fantastic btw, it's just v. annoying having to drain the water off first!

theyoungvisiter Fri 09-Oct-09 20:53:24

ok, here is my method.

Peel and slice potatoes - doesn't matter what type but king edwards are good.

Layer up with finely sliced onion and crumbled goats cheese or grated parmesan. If using goats cheese then you might want to add a little salt.

Pour over cream until you can just see the liquid touching the top layer of potatoes. It should NOT cover the potatoes completely, but will bubble up and cover them during cooking. Sprinkle a little goats cheese/parmesan on top.

Baking times depends on amount of potato but it is impossible to overcook, so I always do it for at least 2 hours at 180 degrees, sometimes 3 hours if it's a big quantity. If it is ready before the rest of the meal then just take it out of the oven and back in half an hour before serving. You can also cook ahead of time and reheat, adding a little milk if it looks as if it's drying out.

You can also use 50/50 cream and chicken stock for the liquid, which is called something else but I forget what. Pommes Boulangere or summat. Tis v yummy.

BonsoirAnna Fri 09-Oct-09 20:56:16

You don't need any milk at all.

Just put potatoes and butter or olive oil or cream in layers in a dish, put tin foil over and put in oven at 180° for an hour or so.

theyoungvisiter Fri 09-Oct-09 21:01:40

the potatoes shouldn't break up, Hopeforthebest, because you don't stir them, and they don't jostle around like boiling potatoes do. There shouldn't be enough liquid for them to bubble and move around.

it sounds like you are either using too much liquid in the first place or not cooking for long enough.

BonsoirAnna Fri 09-Oct-09 21:04:18

The potatoes should cook in their own steam/liquid, with the fat. The important bit is to make sure the tin foil is pretty much air tight, so that the steam doesn't escape.

We had a gratin of potatoes and porcini this evening and the potoatoes and porcini were cooked to a turn and there was no extra liquid.

BecauseImWorthIt Fri 09-Oct-09 21:06:54

Well, I always use floury potatoes

a) they don't break up
b) I don't have the watery problem that you have!

theyoungvisiter Fri 09-Oct-09 21:07:06

but IMO you do have to remove the foil at the end, to get the lovely burnt bits.

I don't like it when the foil is left on for the whole time - the top is too flabby and not "gratinated" enough.

BonsoirAnna Fri 09-Oct-09 21:11:22

Yes, I agree; obviously my potato and porcini dish didn't require that, but anything creamy or cheesy will need 5-10 minutes without foil at the end, with the oven on full heat or else you can just whack it under the grill.

Sorry, I meant they break up when serving, whereas more waxy ones stay in beautiful thin slices.

I think the amount of liquid I'm cooking them in is ok - only just to the top layer of potatoes, as theyoungvisiter says.

Recipes I've seen seem to vary between using just milk, just cream or half-half, but flavourwise I think I actually prefer just milk. I didn't notice any difference when using half-half re. the water.
I'm cooking it for 1 hour, uncovered. The potatoes are cooked, and the whole thing tastes lovely (I usually layer some cooked leek and ham or bacon in between too, with the cheese).

Maybe I'm making it too high? How many layers do you lot usually do? (I'm thinking about evaporation here).

theyoungvisiter Fri 09-Oct-09 21:17:25

I do it in a lasagne dish, so maybe 7cm deep, and the dish is about 30cm by 20cm?

The other thing might be if you are slicing the potatoes too thickly and/or packing them too loosely, if there is a lot of space between the chunks then obviously there will be more liquid in there.

Or of course leeks have a lot of liquid of their own. Are you using a lot?

Basically though, if it tastes nice I would just say do the same thing but pack the potato more closely and cook for half an hour longer, uncovered. The extra liquid will evaporate if you give it long enough.

But the bottom line is that potatoes vary according to season, so you'll need to adjust it and cook it for as long as it needs on any given day.

I fry the leeks and ham/bacon before, so there's no liquid there as such (only using 1 leek).
I overlap the potatoes, but maybe I do need to do it more closely. And I'll add on another 1/2 hour and see if that makes a difference.

Thanks for all the replies, this is so much more useful then trawling the internet trying to compare and contrast a hundred different recipes!

I'm feeling rather touched that so many of you can be bothered to share your potato gratin experiences....
<oh my goodness, is it that time of the month already?>

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