3cupsgranulated sugaryou can substitute an artificial sweetener
1cupfresh lemon juicefrom 4 large lemons
2cupsfresh grapefruit juicefrom 2 large grapefruits
4cupsSprite / 7Up + extra for mixing before servingyou can substitute Sprite/7Up Zero or sparkling water
In a large saucepan over a high heat, stir together the water and granulated sugar or artificial sweetener. Bring to a boil and then reduce the heat down to medium-low. Leave to bubble for 10 minutes, until the sugar/sweetener has completely dissolved.
When the simple syrup has cooled, stir in the rest of the ingredients (pineapple juice, vodka, lemon juice, grapefruit juice and 4 cups of Sprite/7Up/sparkling water). Place the container in the freezer for at least 24 hours to set.
When you're ready to serve, use an ice cream scoop to scoop out enough of the lemon vodka slush to fill a glass and pour over extra Sprite/7Up until it reaches the rim. Mix the drink with a straw or spoon to make it slushy then serve immediately.
1 glass is 180 calories if you use zero-calorie artificial sweetener and zero-calorie Sprite/7Up/sparkling water.