Pour roughly a 1/4 inch of simple syrup into the bottom of a large glass. Add the juice of half a lime (or more to taste) and stir to combine. Top with 12 oz club soda.
Soda chanh is my favorite drink to order at Vietnamese restaurants. Normally it comes to the table all mixed up but I’ve even had it served in a “make your own” version -a can of club soda, a cup with sugar in it and a lime. It is basically a tart limeade made with some sort of sparkling water (generally seltzer or club soda) instead of still water. It is really fresh tasting and easy (and often cheaper!) alternative to regular soda. I have also seen it made with lemon instead of lime and with a sprinkle of salt. I like to make it using simple syrup instead of just stirring in sugar for a few reasons: you don’t get even a hint of gritty sugar, it dissolves nearly instantly so you aren’t left with undissolved sugar at the bottom of your glass and you don’t lose the bubbles in the soda by stirring it. Simple syrup can be stored in the refrigerator for months so you can make a batch and have it ready to make fresh lime soda any time. The recipe is simple and can be adapted to serve as many or as few as you want. I do recommend make each serving separately rather than making a whole pitcher at once for maximum bubbles. If you pour the soda into the pitcher and then pour it into glasses, it loses most of the fizz and you might have well just made limeade.