Add the tomatoes, cucumber, celery, grapes and jalapeno to a blender and puree. Line a sieve with cheesecloth, set over a large bowl and pour in the pureed mixture. Set the bowl in the refrigerator while it strains, about 30 minutes.
Once the liquid has been extracted, remove the bowl from the refrigerator and discard the solids. Combine the horseradish, superfine sugar and 2 lime wedges in a pitcher and muddle with a wooden spoon. Stir in the tomato juice mixture, the vodka and some crushed ice until combined.
Combine 1 tablespoon each salt and pepper on a small plate. Rub a lime wedge around the rim of each glass, then dip the glass in the salt and pepper mixture. Pour the drink into glasses and garnish with cucumber spears and a few grape halves.