Preheat oven to 200° F. Line a cookie sheet with parchment paper, and place the limes on the top 1-inch apart. Bake the limes for one hour. Flip, and bake for another 30-60 minutes, until the limes are dry and crackly. Let cool completely, and store in an airtight container until ready to use.
Prickly Pear Vodka Sour
In a cocktail shaker, combine the vodka, lemon juice, lime juice, and prickly pear syrup. Fill the cocktail shaker with ice, and shake until the outside is frosty, about 30 seconds. Strain into a cocktail glass and garnish with dehydrated limes or herbs. Serve immediately.