I don't have any preserved lemon in the house, and don't have a place to buy them locally. What can I use as a substitute?

Lemon zest would work, but there is an unique soft flavor to preserved lemons. In a pinch I would try cutting the lemons into wedges, scrape out the meat and most of the white pith, then boil in salted water until the skins become soft. Rinse, chop, use. But, do try making your own, as noted above, it is just lemons, salt and water. You only use the skins - but I have seen them in all kinds of home recipes, including pizza with shredded moroccan spiced lamb !

I've found lemon zest (or in a pinch, lime zest) to be the best substitute for preserved lemons. Depending on the recipe, in addition to the zest, you may want to add a dash of fresh lemon juice. Ideally, assemble as much of the dish as you can, then taste and decide if you want to add any fresh citrus juice in addition to whatever lemon zest you added.
I've tried several times but no success with recipes for "same day" preserved lemons including the Nytimes.com recipe mentioned above - recipe instructions followed to the letter. The final dish tasted very off, but trying the same recipe again with fresh lemon zest instead worked fine.
Preserved lemons are easy to make - no need to spend on imported. Just do a search on this web site or a web search for a recipe. Just lemons, coarse salt and lemon juice, marinating for 30 days. Very versatile - worth the little bit of effort.

I wanted to do the quick preserved lemons, but didn't find the time. I also didn't find the time to stop and buy olives, so I just went with lemon zest and salt. It was delicious! I will definitely make again, hopefully with preserved lemons next time.

Hi Sunnyluz,
Sorry for the late reply, I just saw your question posted on twitter (did not get a notification email). Both nutcakes and hardlikearmour have good suggestions - I had not seen that article about quick preserved lemons but am definitely going to save it! If you go the route of just using lemon zest, you may want to add some salt to taste at the end since the preserved lemons do give the salad bursts of salty bright flavor. Or, you could also add a few chopped olives - maybe castelvetrano? I'd love to hear what you end up trying and how it works out.

You could also sub lemon zest. It won't be quite the same, but will be a decent approximation - I'd probably start with 2 teaspoons, then add more to taste.

I've made emergency quicky ones from fresh lemons and they work in a pinch and add the lemony flavor. Here's one or keep googling:
http://www.nytimes.com/2010/10/20/dining/20mini.html?_r=2&ref=dining