Make the syrup by adding the water and sweetener to a small saucepan. Bring to the boil and cook until the sweetener has dissolved and the mixture has reduced by half. Let cool fully. Mix in some pomegranate concentrate and red food dye.  Set aside.

Fill four tall glasses with ice and add two tablespoons of tequila and one cup of the orange water to each glass. Stir to combine.

Slowly add a tablespoon of grenadine syrup to each glass. It will sink to the bottom, so that the top of the drink remains lighter and has a more orange hue.

Garnish with the orange slice, if using.