This is the blue cocktail of my dreams! It's a fairly simple gin sour, but with a gorgeous blue hue and an indigo gin layer on top. The blue color comes from both blue spirulina powder and a butterfly pea flower-infused gin.
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Creating the Blue Color
When I envisioned this cocktail, I knew I wanted a bright blue color, but I didn't want the orange flavor of blue Curaçao. I wanted a light, bright citrus flavor.
Enter blue spirulina powder! (affiliate link) This stuff is really neat. I also used it in these Boozy Firecracker Popsicles for the blue layer. It's made of a type of algae, but doesn't have much of a taste, just a super-vibrant color. A little goes a long way!
Float of Indigo
When I saw the color that the blue spirulina created in the drink, I wanted to add a little something extra to deepen it up a bit and bring some more visual interest. I decided to float Empress Gin on top. Empress is infused with butterfly pea flowers, which give it a deep indigo color.
The cool thing about butterfly pea flower infusions is that the color changes to purple/pink when it comes in contact with something acidic. This is the same thing that hydrangea do depending on the pH of the soil they grow in. (Hydrangeas are the flowers in the background of my photos -- although you can't eat them!)
How to Float, and Why It Works
The science behind the float
Creating a layered cocktail, where two liquids don't get mixed together, can be a challenge. But, it gets much easier when you understand the science behind it. Basically, it's all about density.
Sugar is the main key here. Although it's not the only factor, as a rule, liquids with sugar tend to be denser than other types of liquid. The more sugar it has, the thicker the liquid, getting closer to being a syrup.
When we mix the bottom part of the cocktail all together, it has simple syrup, which makes the whole thing thicker than just gin. That way, you can use the plain gin to make a layer on top.
How to make it work
The how-to takes a little practice to master. In the photos below, I am just pouring it straight from the bottle onto a spoon, which softens the stream into the glass. However, I definitely recommend using a jigger and measuring first, then pouring from the jigger. That way you won't get a big old mess like in the photo on the left!
I found that you can hold the spoon either way. I personally prefer to hold it with the spoon bowl facing up, but I know a lot of bartenders hold it the other way. You can also hold the spoon where it is either touching the side of the glass or getting close to the side. This might help if you're having trouble getting it to work.
Ice or No Ice?
It may be a little weird to put ice into a coupe glass, but I knew it would look great with the blue color! You can serve it however you like. The float will still work, with or without ice. If you don't use ice, I would suggest chilling the glass really well with an ice-and-water slush before straining the drink into it.
If you aren't making your own clear ice, try to use the ice that they sell in the grocery store. It's inexpensive and you can just store it in your freezer for a fancier look to your cocktails!
Making the drink
Despite the fancy look, this is a fairly straightforward gin sour. The difference is that we have to mix the blue spirulina powder into the liquid. You can probably just do this in the shaker, but I wanted to make sure it was all dissolved, so I stirred it in with a bar spoon.
Once the lime juice, blue spirulina powder, simple syrup and clear gin are measured out, shake everything with ice and strain into your serving glass. Double strain (with a regular cocktail strainer plus a fine mesh strainer) if you want to make sure you get out any lime pulp.
Then, just float the Empress gin on top like explained in this section above.
If you want to change up the cocktail, try using a vodka or white rum instead of gin as the base spirit. You can even infuse your own clear spirit with butterfly pea flowers (affiliate link) if you want to make the darker float with that same spirit!
Other Cocktails You Might Like
- These Boozy Firecracker Popsicles also use blue spirulina for color
- This Gin and Violet cocktail is a fairly simple sour, but with a violet twist
- Another refreshing drink, the Gin Campari Sour is another brightly-colored cocktail
Did You Try This Recipe?
I would love to hear from you if you made this recipe, or if you have any questions about it! How did you like using the blue color powder? Please consider leaving me a star rating or a comment below if you like it!
📖 Recipe
Cerulean Sour
Equipment
- Cocktail shaker
- Cocktail strainers (optionally two strainers)
- Serving glass (I used a large coupe)
Ingredients
- 1 oz lime juice freshly squeezed
- ⅛ teaspoon blue spirulina powder
- 1 oz clear gin
- 1 oz simple syrup
- 2 dashes lemon bitters
- ½ oz purple gin Empress, or your own butterfly pea-infused spirit
Instructions
- Mix together the lime juice and blue spirulina powder until the powder is fully dissolved.
- Add the gin, simple syrup and lemon bitters.
- If you are using ice, add it to your serving glass. If not, chill your serving glass with a slush of water and ice.
- Shake the drink mixture with ice, about 15-20 shakes.
- Strain into your serving glass.
- Measure the purple gin into a jigger. Slowly pour the gin onto the bar spoon, held over the top of the glass, so that the gin forms a darker layer on the top of the drink.
- Serve immediately.
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