To make each cocktail, place 2 sprigs of cilantro into a cocktail shaker. Bruise lightly with a muddler or wooden spoon. Add 5 ounces of the Bloody Mary base, 2 ounces of vodka, 1 teaspoon horseradish, 3/4 teaspoon of green hot sauce, and a pinch of celery seeds to the shaker. Add ice halfway up, and stir about 10 times to combine, until the shaker is cold. Pour the drink with the ice into a glass, and garnish with a lime wedge, cilantro, and tortilla chips and a green onion, if using.