Sauce Piquante — Sharp Gherkin and Caper Espagnole

Piquante is demi-glace sharpened with a white wine and vinegar reduction, garnished with cornichons, capers, tarragon, chervil, and parsley. It is the sauce for leftover meats — specifically, rôti de porc réchauffé (reheated roast pork) — and its genius lies in using aggressive acidity and pungent garnishes to compensate for the flavour loss that occurs when meat is cooked, cooled, and reheated. In a tradition that wasted nothing, Piquante ensured that yesterday's roast tasted as compelling as today's. Sweat 2 tablespoons of finely minced shallots in butter until translucent. Add 100ml of dry white wine and 50ml of white wine vinegar. Reduce by two-thirds — the reduction should be intensely sharp, almost uncomfortable to taste alone. Add 400ml of demi-glace and simmer for 15 minutes. Strain through a fine chinois. Prepare the garnish: 30g of cornichons (the tiny French gherkins, not American dill pickles), cut into 3mm rounds; 1 tablespoon of small capers, drained and rinsed; and 1 tablespoon each of chopped tarragon, chervil, and flat-leaf parsley. Add the cornichons and capers to the hot sauce. Add the herbs off heat — they discolour within seconds in hot liquid. The finished Piquante should taste sharp first (the vinegar reduction), savoury second (the demi-glace), and finish with bursts of brine (capers, cornichons) and fresh herb. It should provoke appetite, not satisfy it — the sauce's role is to make you want to eat more of the meat it accompanies. Piquante and Sauce Charcutière share parentage — Charcutière is essentially Sauce Robert (mustard-onion espagnole) with the same cornichon garnish. The two sauces sit side by side in every classical reference because they solve the same problem (sharpening pork) from different angles: Piquante through vinegar and herbs, Charcutière through mustard and onion.