1. In a shaker tin, combine the sherry, tomato water syrup, and lemon juice with ice. Shake just long enough to chill, then strain into a cocktail glass with crushed ice.Garnish with a green shiso leaf and a cherry tomato. Dust with powdered sugar.

For the tomato water syrup

1. Stem, core, and coarsely chop 1 pound vine-ripened tomatoes. Place in a blender and blend on high until smooth. Line a sieve with a dampened kitchen towel or thick paper towels and set over a bowl. Pour the tomato puree into the lined sieve and let sit. It will take about 1 hour to yield about 10 ounces of tomato water. Weigh the tomato water and mix it with half of its weight of granulated sugar and a pinch of salt, to taste. Mix until fully homogenized. Store refrigerated for up to 1 week, or portion into ice cube trays and store in your freezer until it is time for a cocktail. Makes about 12 ounces.