Furnas, São Miguel, Azores, Portugal
The most extraordinary cooking technique in the Portuguese world — and one of the most unusual in global gastronomy. On the island of São Miguel in the Azores, the cozido das Furnas is lowered in sealed pots into the volcanic fumaroles (bubbling sulphur vents) at Caldeiras das Furnas and cooked for 6-7 hours by geothermal heat. The temperature in the fumaroles is approximately 95-100°C — just below boiling, perfect for a gentle, sustained braise. The result is the same as cozido à portuguesa (beef, pork, chouriço, morcela, blood sausage, chicken, potato, cabbage, yam, carrot) but with a faint mineral note from the volcanic environment — a flavour that cannot be replicated anywhere else on earth.
The technique requires sealed iron or aluminium pots placed directly into the fumarole holes, covered and weighted to prevent steam from displacing them. The cooking time is fixed by the geothermal temperature — 6-7 hours minimum. The result is extraordinarily tender meats — the long, low-temperature cook converts collagen to gelatin and produces a broth of deep complexity. For service outside the Azores: replicate using a slow cooker at 90°C for 8-10 hours.
The restaurant Tony's at Caldeiras das Furnas has been serving the geothermal cozido since 1959 — they lower the pots each morning at 6am for a 12pm service. For the Azorean context specifically, the local varieties of cabbage (couve crespa), potato, and yam are different from mainland Portuguese varieties and contribute to the regional specificity. Pair with Pico Island wines — Verdelho from the volcanic Pico appellation (one of the world's only UNESCO-protected wine cultures) is the correct wine.
Attempting to replicate the volcanic mineral character artificially — it cannot be done. Using a higher-temperature slow cook — the gentle 95°C is essential.
Leite's Culinaria — Portuguese tradition