Take one of the mildest vegetables in the kitchen and the seasoning becomes the entire point. Courgette has a clean, faintly green flavour and almost no salt or acid of its own, so a sandwich that simply piles it on tastes of very little. The defining element is the courgette grilled: sliced thin lengthways, marked over heat until soft and lightly charred, then salted while still warm and brightened with a squeeze of lemon or a few drops of vinegar before it goes into a split crusted loaf. The salt and acid are not optional garnish here; they are what makes the vegetable read at all.
The craft follows from that blankness. Grilling concentrates the courgette and adds a thread of char, which gives the flesh somewhere to start, but the sandwich still leans on what you add: salt to wake it, acid to give it edge, often a herb or a little olive oil to carry both across the crumb. Courgette also holds water under its skin and softens further as it sits, so the slices want to be cooked through and rested briefly rather than gone in straight from the pan. The bread needs a real crust because the filling is soft and mild and brings no structure or assertiveness of its own; the crust is much of the sandwich's character. Eaten within a few minutes of assembly the bread still has bite and the seasoning is at its sharpest.
Variations stay in the light Mediterranean register. The same loaf takes the courgette layered with roasted pepper and aubergine into a cooked-vegetable build where the other two carry more weight; or ribbons of raw courgette dressed hard with lemon and oil for a fresher, crisper read; or a smear of fresh goat cheese underneath to give the mildness a tart, creamy partner. Each holds the bread and the discipline constant and changes only what stands with the courgette. The Sandwich aux Courgettes belongs with the plant-forward builds the catalog groups under Sandwich Végétarien. Its specific contribution to that shelf is a deliberately quiet vegetable whose sandwich is mostly an argument for salt, acid, and a good crust.