One olive carries the whole sandwich, treated as the entire point. The Picholine of Nîmes is firm and green, crisp-fleshed and bracingly bitter, and here it works in the tapenade register: the olives crushed or chopped, often with a little oil and the bitterness left intact, spread thick on split bread. It belongs to the Gard, where the Picholine is the local olive and the crushed-olive paste is a standard of the regional pantry. The olive is not a garnish here; it is the spread the sandwich is named for.
The craft follows from how strong the olive is. Picholine paste is salty, bitter, and oily all at once, which means it does not need a rich partner and would overwhelm a delicate one. The bread carries it like a condiment, so a firm crust matters: the paste soaks slightly inward and softens the crumb, and a weak loaf goes slack under it. The discipline is restraint, the same logic as a tapenade sandwich, where the olive does the talking and anything else is there only to frame it, a thin layer of fresh cheese to round the bitterness, a tomato slice for moisture, nothing that competes. It is a cold sandwich, eaten plainly, and it holds up well because oil and salt are stable.
Variations stay in the Provençal olive register. A round of soft goat cheese tempers the bitterness; a few capers or an anchovy push it toward the full tapenade; ripe tomato lightens it for summer. The Sandwich aux Olives de Nîmes belongs with the plant-forward builds the catalog groups under Sandwich Végétarien. Its specific contribution is the Nîmes Picholine itself: a sandwich that puts a single regional olive in the lead and builds nothing that gets in its way.