70 ml Rutte Old Simon jenever
25 ml Combier triple sec
15 ml Campari
5 ml agave syrup
Orange zest as garnish
Preparation: Stirred. Sprinkle with an orange zest and garnish.
When he tasted a bottle of Old Simon jenever from Rutte, he was inspired to create this variation of a gin cocktail. It was based on the “Gin Cocktail” published in Jerry Thomas’ 1862 book “The Bartender’s Guide” on page 51: 
Gin Cocktail. Jerry Thomas, 1862.
(Use small bar glass.)
3 or 4 dashes of gum syrup.
2 do. bitters (Bogart’s).
1 wine-glass of gin.
1 or 2 dashes of Curaçoa.
1 small piece lemon peel; fill one-third full of fine ice
shake well, and strain in a glass.
Salvatore Calabrese modified this gin cocktail by making it with jenever, replacing the Boker’s Bitters with Campari and thus giving the cocktail an Italian touch. The orange zest instead of the lemon zest picks up the flavours of the curaçao and Campari and rounds off the drink. 
The cocktail was named after the Old Simon jenever. This jenever is distilled according to an old recipe by Simon Antonius Rutte from 1872. The latter is the eponym for both the jenever and the cocktail. 
We have found that a large number of recipe variations can be found. We have listed some of them in the appendix. Everyone seems to vary this drink a little according to their personal preferences. We liked Combier in this drink better than Mandarine Napoléon or the Curaçao from Pierre Ferrand. We also prefer a little more Campari, as it adds a little more complexity to the drink.
- http://ruttedistillery.com/Cocktails/mr-simon/: Mr. Simon. A bittersweet apéritif inspired by Salvatore Calabrese.
- https://www.youtube.com/watch?v=00GPyXh335M: Mr. Simon cocktail. By Salvatore Calabrese, 30. December 2015.
- https://www.diffordsguide.com/cocktails/recipe/3627/mr-simon: Mr. Simon.
- This photo was kindly provided by Rutte.
http://ruttedistillery.com/Cocktails/mr-simon/: Mr. Simon. 2 pts. Rutte Old Simon Genever; 1/2 pt. Mandarine Napoléon; 1/6 pt. Campari; barspoon agave syrup; 1 orange zest; Add all ingredients and stir until cold and diluted. Strain into a chilled cocktail glass and garnish with an orange zest.
https://www.diffordsguide.com/cocktails/recipe/3627/mr-simon: Mr. Simon. 2 shot Rutte Old Simon Genever; 2/3 shot Pierre Ferrand Curaçao; 1/3 shot Campari Bitter; 1 spoon AquaRiva agave syrup; garnish: orange zest.
2015 Salvatore Calabrese auf https://www.youtube.com/watch?v=00GPyXh335M. Mr. Simon. 60 ml Old Simon jenever; 20 ml orange curaçao; 10 ml Campari, 5 ml agave syrup; garnish: orange zest.
2016 Rutte-Flyer auf dem BCB 2016. Mr. Simon. 60 Old Simon, 15 Orange Curaçao, 10 Campari, 5 Agavensirup.
2017 Le Lion, Hamburg. Mr. Simon. 70 ml Old Simon Jenever, 25 ml Dry Curaçao, 10 ml Campari, 1 Barlöffel Agavensirup.