Bari and the surrounding Pugliese coast. Tiella (the name comes from the terracotta dish) is documented in Pugliese cooking records from at least the 17th century. The combination of rice, potato, and shellfish reflects the Pugliese tradition of layering the carbohydrate staples of the region's poor with the seafood of the Adriatic coast.
Tiella is the archetypal baked dish of Puglia — a layered casserole of rice, potato, and mussels baked in a terracotta dish with olive oil, onion, garlic, Pecorino, and breadcrumbs. The rice is raw when it goes in and cooks in the mussel liquor released during baking — absorbing the brine and sweetness of the mussels. It is one of the fundamental expressions of Pugliese cucina povera: a complete one-dish meal requiring minimal technique and producing extraordinary flavour.
The mussel liquor, absorbed into the raw rice during baking, creates rice with a deep brine-and-sea flavour that no stock can replicate. The potato provides starchy sweetness; the tomato provides acid; the Pecorino-breadcrumb crust is savoury and crunchy. The tiella at the table smells of the sea.
The layers are specific: onion and tomato on the bottom, then raw mussels (opened raw by prying — not cooked open), then raw rice (arborio or short-grain), then sliced potatoes, then another layer of onion-tomato-mussel-rice, ending with breadcrumbs and Pecorino. Olive oil generously throughout. The liquid is the mussel liquor — no added water or stock — poured over the assembled tiella. Cover tightly with foil and bake at 200°C for 45-50 minutes until the rice is cooked and has absorbed all the liquid, then uncover for 10 minutes to brown the top.
The resting time after baking is essential — 10-15 minutes covered allows the rice to finish absorbing any remaining liquid and the layers to firm up for serving. The tiella should come away clean from the sides of the dish. Use a terracotta tiella if available — it distributes heat evenly and absorbs excess moisture, producing a better result than metal or ceramic.
Cooking the mussels before assembling — the raw mussels open during baking and their liquor is absorbed into the rice; pre-cooked mussels release no liquor and overcook. Adding extra water — the mussel liquor is the liquid; more water dilutes the flavour. Not using Pecorino in the breadcrumb layer — it forms a savoury crust. Slicing potatoes too thick — they won't cook through in the baking time.
Elizabeth David, Italian Food; Slow Food Editore, Puglia in Cucina