When Moko makes this at Mokoloco, she makes the "base," which is the recipe below. When an order comes in, she pours some in a glass, then adds an equal amount of cold water to it. The best kinds of cucumbers to use are the long cucumbers, often referred to as English cucumbers, although they're sometimes just called "seedless" or less-elegantly, "burpless." Smaller Persian cucumbers could also be used. The plump, seedy cucumbers usually sold in American supermarkets (the Dasher variety is one such cucumber) can have tough skin and those pesky seeds. If you use one of those, you probably want to remove a little over half of the skin, and definitely scoop out the seeds (which can be bitter) as well. Because you are using the skins, organic cucumbers and limes are preferable, although not always available. Moko told me she sometimes uses as much as 80-100g (1/3-1/2 cup) fresh lime juice. An average lime yields about 2 tablespoons of lime juice. I found that too much overwhelmed the other ingredients, but feel free to add additional lime juice, more than I used in the recipe below, to taste. I also toggled the amount of sugar; you can start with the smaller amount (6 tablespoons/75g) and add more if you'd like. If you have a high-powered blender, this is a great place to use it.