Any allergy or diet, understood in Spain.

Paella and rice dishes cooked in shellfish stock · paella de marisco / arroz a banda / arroz caldoso / fideuà

Even nominally shellfish-free paella and rice dishes are routinely cooked in caldo de marisco (shellfish stock), saturating every grain with shellfish protein. Many restaurants proactively turn away shellfish-allergic diners rather than guarantee safety, and fideuà uses the same stocks in noodle form.

Highest-impact Spain-specific risk. The shared shellfish stock is most common in restaurants that primarily serve seafood paella; dedicated chicken paella kitchens may use chicken stock. Verify per establishment. Fideuà also adds gluten via noodles.

Romesco sauce · salsa romesco / salsa de calçots

Romesco is a Catalan sauce built on roasted almonds and/or hazelnuts blended with dried peppers and tomato. Its dark red-orange color gives no visual cue that nuts are present, and it is served as a default dipping sauce for calçots, grilled meats, and fish, often without being named on the menu.

The sauce for calçots is technically 'salsa de calçots' (almonds only, thinner), while romesco proper uses both almonds and hazelnuts. Pine nuts may also appear. The hidden-nut risk via visual appearance is confirmed by multiple food allergy travel guides.

Picada (Catalan nut-thickening paste) · picada catalana

Picada is a paste of ground almonds, hazelnuts, or pine nuts blended with fried bread and garlic, stirred into Catalan braises, fish stews, and fideuà during the final minutes of cooking. It leaves no visual trace, and because cooks treat it as a finishing technique rather than an ingredient, they may not mention it when asked about nuts.

The nut-and-fried-bread composition and invisible use as a thickener are documented. Because picada is added as a finishing step, ask specifically whether a braise, stew, or fideuà is finished with picada rather than only asking whether the dish 'contains nuts.'

Shared deep fryer in tapas bars · freidora compartida

A single commercial fryer is used continuously for calamares, gambas, croquetas, patatas bravas, boquerones, and churros throughout service. Any item fried after shellfish or breaded fish carries shellfish protein, fish protein, and gluten in the cooking oil.

A shared fryer is standard in Spanish tapas bars and is the primary cross-contamination vector for shellfish, fish, and gluten when ordering otherwise-safe fried items. Legal Nomads flags confirming fryer status as critical for celiacs, and Food Allergy Getaways warns that fried tapas carry seafood cross-contact. Ask whether there is a dedicated fryer.

Pork hidden in legume and vegetable dishes · lentejas / cocido madrileño / fabada asturiana / caldo gallego / menestra de verduras

Spanish lentil soups, bean stews, chickpea cocido, and even vegetable menestras are traditionally cooked with chorizo, morcilla, tocino, pork bone stock, or lard. A server confirming a dish is vegetarian may mean it contains no whole pieces of meat while the broth is entirely pork-based.

Fabada asturiana compango (chorizo, morcilla, tocino) is definitional; cocido madrileño includes pork belly, chorizo, morcilla, and jamón serrano; caldo gallego uses unto (pork lard) as essential flavoring. The linguistic confusion around 'vegetarian' in Spain is extensively documented.