Ti Punch
The lime disc in the drink is garnish enough but also consider expressing a lime zest twist over the drink and then discarding.
Traditionally the limes used to make this drink are not cut into slices or wedges. Instead, a round disc is cut from the side of the fruit. These are cut large enough that some of the fruit's flesh backs the peel of the disc.

POUR the rum and sugar into glass. Then SQUEEZE the lime disc between finger and thumb before dropping into the drink. This expresses the oil from the skin and little of the juice into the Ti'Punch. STIR and consider adding ice - either one or two large cubes depending on glass size, or preferably, a small chunk of block ice.
[['4.5 cl', 'Martinique blanc rhum agricole'], ['0.75 cl', 'Clement Sirop de Canne'], ['1 slice', 'Lime (fresh)']]
[['4.5 cl', 'white rum'], ['0.75 cl', 'clement sirop de canne'], ['1 slice', 'lime']]