Just like at Porto’s central Campanhã train station on Rua da Estação, O Astro Cervejaria Petisqueira on the other side of the street is reliably crowded every day. Its strategic location near the station helps account for that. But what really draws the crowds in is O Astro’s reputation as a must-stop for the definitive take on the bifana, one of Porto’s signature sandwiches. Much like the train station, O Astro brings locals and visitors together from all over Portugal, in search of one of Porto’s essential bites. At the most elemental level, the bifana is a pork sandwich, and in its most traditional form it includes thin slices of braised pork shank tucked into a crusty roll called a carcaça.

You would think Sérgio Oliveira, the owner of Conga in Porto and the secret-keeper of its legendary recipe for bifanas, would be tired of the restaurant’s signature dish. But you’d be wrong. “As much as I try not to eat it, I cannot. It is impossible,” he says. "One always eats it; there is no chance not to.” It’s a simple but addictive dish. Pork, cooked all day in a mysterious spicy sauce and stuffed into a piece of bread that looks a bit like a roll– at first glance, it does not seem to impress. But Porto continues to hide the best and tastiest of its secrets in the simplest things in life.