The Paleo community calls these NorCal margaritas. I believe Robb Wolf invented the recipe. They are low carb and tasty without any added sugar.
What you need:
1 cup club soda
1-2 shots of tequila (this makes or breaks it so buy your favorite)
The juice from half a lime
Pour all the ingredients over ice. Stir and serve! You can garnish with lime, add other fruit, or mint would be yummy!
Nutrition notes: Alcohol has zero nutritional value, but is ok when consumed in moderation. (Who didn't know that already?) Club Soda is simply bubbly water so drink all you want! Limes are a great way to get Vitamin C, and antioxidants. They also aid in digestion.