Here in Texas, we get Mexican limes, which are very similar to the fruit known as Key limes.
Key or Mexican limes are small and round. They are about an inch or two in diameter. They are thin-skinned, fragrant, and bitter when green but sweeter when they ripen to yellow.
The common lime available in most grocery stores year-round is known as the Persian lime, and it is less tart and less acidic than a green key lime. If you want to make authentic Key lime desserts, you might want to go to a little extra effort to find Key limes. The Persian lime will work but it will taste a little bit different.
It is somewhat difficult to extract the juice from a Key lime, but here is what I learned through experience and a little bit of research:
- Bring limes to room temperature so that they yield the optimal amount of juice
- Roll the fruit on the counter to break the cell membranes
- Cut the fruit from pole to pole, like THIS:
NOT this (although these look prettier!):
- Use a fork to poke the exposed fruit, then use the fork as a reamer (or use a garlic press or a citrus press like this):
I had two pounds of Mexican limes and they yielded about 2/3 cup of juice. It was enough to make 2 dozen Key Lime Cupcakes and frosting, and I still have some juice left for another day.