I'm making a potato leek soup and I'd like to just throw all the ingredients into a slow cooker and go about my business, pureeing the whole batch and adding cream later.

Does this sound reasonable or do I need to first "sweat" the leeks in butter as I would onions?

4 Answers 4


When cooking in a slow cooker, you do not have to precook the leeks. I made a potato leek soup not too long ago that called for throwing everything in the pot and it came out great. The only thing I cooked before hand was the bacon, rendering out much of the fat and giving the nice golden brown and crispy bits to sprinkle on top.

You CAN precook anything to help reduce the cook time and I always sear meat, but unless you are going to caramelize the leeks, you will not notice any difference in flavor or texture.

As for the pureeing part, you want to be careful pureeing potatoes as they can turn into a nasty gluey mess. Just keep it to a minimum or use a food mill and you should be fine. I typically just use a potato masher and leave my soup a little on the chunky side.


The soup turned out just okay. The leeks did soften well in the water, and the soup did puree well, but I feel like there were some flavors in the end result which wouldn't have been there if I'd sauteed the leeks in butter.

We pre-cook our alluims (garlic, onion, leeks) to soften, but also to drive off unpleasant sulfur compounds which affect the end result. I feel like this would've been a better soup if I'd taken the time to soften the leeks in butter.


Most recipes that I have seen for potato and leek soup all call for softening. None of them use a slow cooker however, as we don't have one. But my suggestion would be to soften before using.


Depends. I suggest if you're using mammoth end of season leeks like you're likely to get now, you should soften them, or be prepared for a loooong time in the slow cooker. In August its not an issue.

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