
Coriander bitters are a cocktail bitters with coriander seed as the defining aromatic.
No single bottle gives both halves of it cleanly, so a swap covers one and leaves the other to the gin.
Orange bitters plus a pinch of coriander
The citrus half comes from the bottle, the warm half from a knife-tip of ground seed, and dash for dash; the drink barely notices the change.
Coriander seed crushed into syrup
Syrup brings the aroma with sugar attached and no strength, which moves the adjustment from the seasoning to the sweetening. It goes in by measure rather than by dash, so the drink’s sweetness comes down.
Coriander seed keeps its citrus-and-sage note well in alcohol, better than the fresh herb ever does in a kitchen. Close it firmly, keep it off a sunny shelf, and it will still be doing the same work in three years.