Harry of Ciro's ABC of Mixing Cocktails by Harry of Ciro's (1923, p.59) — Harry of Ciro's 1923
| 0.5 part | lemon juice — Lemon Juice | acid |
| 0.63 part | gin — Source OCR reads 5 as the leading measure; treated conservatively as five-eighths to match the book's prevailing fractional style. | base |
| 0.5 part | creme de cassis — Cassis | modifier |
- Shake well and strain into cocktail glass.
This matters because it keeps a cassis-and-gin sour branch visible in a London 1923 source rather than only in later revival material.
The value here is the compact three-part sour structure without later soda or fruit garnish elaboration.