Vinagreta para Fiambre Potosino

San Luis Potosí, in the high central plateau, owns this vinagreta because the fiambre potosino owns the table at family celebrations there. This is not a flashy salsa. It is the quiet liquid that does the work overnight: vinegar, oil, mostaza, tomillo, mejorana, orégano, salt, and patience.

The geography matters. Potosí sits between the Bajío, the Altiplano, and the Huasteca, and its cooking reflects that crossing of roads. Fiambre potosino is a cold composed dish, meat, vegetables, sometimes cheese, all dressed ahead so the vinegar can enter instead of just shining on the surface. The señoras who make it well know restraint. Too much mustard and it tastes foreign. Too much oil and it goes heavy. Too little salt and the vegetables taste asleep.

I learned a version from a woman near the Mercado Hidalgo in San Luis Potosí capital, and she corrected me before I even opened the vinegar. 'No lo bañes al final,' she said. Don't pour it at the end. The fiambre must rest. That is the technique. La cocina no es decoración, es trabajo.

Use apple vinegar, not white vinegar. Use dried Mexican oregano, not Italian oregano pretending to understand the job. Crush the herbs between your fingers before they go in. The aroma should wake up immediately. Recetas probadas y garantizadas, but only if you give the vinagreta the night it needs.