Using a spoon, scoop out citrus from limes. Dunk lime "shot glasses" in water to rim the edge and then dip in salt. Set aside.
In a blender, combine tequila, triple sec, lime juice, and ice and blend for 1 minute until it's a thick slushy texture. (Move around mixture with a wooden spoon if ice chunks remain.)
Use a small ice cream scoop to scoop mixture into limes.
Garnish with lime zest and serve.
Recipe by 5* trending recipes with videos at https://food.theffeed.com/2017/05/02/margarita-slushy-shots/