Add around 3–4 threads saffron per liter of gin. Stir. Let stand for an hour.
Combine all ingredients for tonic and bring to a boil. Once it begins to boil, reduce heat and simmer for 20 minutes. Strain through chinois and chemex.
When ready to serve drink, build first 4 ingredients in Collins glass and stir. Add quality ice cubes. Grate nutmeg, then express the lemon peel and use for garnish.