If you juice the blood oranges yourself be sure to pass the juice through a fine strainer to remove any fruit pulp. Do the same for the lime juice. Since we are adding a carbonated component in the form of sparkling water to finish the drink, we want the liquid to be as clear as possible. Solids like those found in juices inhibit the effects of carbonation.
For the same reason we’re going to chill all of our non-carbonated drink components together with plenty of ice so all liquids are as cold as possible before adding the sparkling water. Carbonation is also inhibited by the heat.
The addition of a pinch of salt does a lot to most drinks to make flavours more pronounced and balance out other flavours. It could be because I associate tequila with margaritas and their characteristic salt rims but it really is one of the spirits that most benefits from a bit of salt. Don’t go overboard, the tiniest of pinches will do, you by no means want this to taste salty.