- On a small flat plate, stir together 3 tablespoons salt and the lime rind; set aside.
- Pour ¼ cup of the lime juice into a shallow bowl and set aside.
- In a blender, combine cucumber, avocado, tomatillos, grapes, cilantro, Serrano pepper, remaining ¼ cup lime juice, celery salt, ½ teaspoon kosher salt, the hot sauce and black pepper; whirl until smooth; mixture will be slightly thick. Transfer to a 2-quart pitcher; stir in coconut water. Add tequila or vodka to taste, if desired.
- To serve, dip glass rim in reserved lime juice, then into salt and lime rind mixture. Add ice and fill with “Guaca Mary”.
- Thread avocado, grape tomatoes and pickled onions onto toothpick or skewer for garnish, if desired.