Tuna has a long history in the Algarve: for centuries, armações de atum, large fixed tuna traps, ringed the coast near Olhão and Tavira, until bluefin catches collapsed in the twentieth century. Tuna was never a luxury in his childhood. It was what came home in the boat, and what his mother turned into supper night after night, usually cebolada style: seared hard, then smothered in a slow, vinegary tangle of onions until it barely resembled the fish it started as.

Atum de cebolada is deceptively plain sounding, tuna with onions, but the magic is in how those onions are cooked. They go in with garlic and a good glug of olive oil and just sit there, low and patient, until they collapse into something sweet and jammy, then get a hit of red wine vinegar and a whisper of sweet paprika that turns the whole pan a rusty gold. The tuna gets seared fast and hard so the center stays rosy, then it rides home on top of that onion tangle, soaking up everything good happening in the pan.

This is made with fresh tuna steaks from the fish counter, a very different thing from canned tuna. If you liked our Bife de Atum à Madeirense (recipe on the site), think of this as its scrappier, saucier cousin from the other end of the country. It is a quick weeknight dinner that tastes like it took much longer, best with rice, boiled potatoes or bread to mop up the onions. For more Algarve fish cooking, our Sopa de Peixe do Algarve (recipe on the site) uses a similar tomato and garlic base.

Atum de Cebolada Recipe

What you need

Ingredients

4 tuna steaks (about 6 oz / 170g each), 1 inch thick, patted dry
Salt and black pepper, to taste
3 tablespoons olive oil, divided
For the cebolada sauce:
2 large yellow onions, thinly sliced
1 green bell pepper, thinly sliced (optional, Tavira-style)
4 cloves garlic, minced
2 tablespoons tomato paste
1 large ripe tomato, chopped (or 1/2 cup canned diced tomato)
2 tablespoons red wine vinegar
1 teaspoon sweet paprika
1 bay leaf
1/4 cup dry white wine (optional)
Fresh parsley, chopped, for serving

Cook along

Instructions

Season the tuna steaks generously with salt and pepper on both sides.
Heat 2 tablespoons olive oil in a large heavy skillet over medium-high heat until shimmering. Sear the tuna for about 1.5 to 2 minutes per side for a rosy center, or longer if you prefer it cooked through. Transfer to a plate and set aside; it will finish cooking gently in the sauce.
Lower the heat to medium and add the remaining tablespoon of olive oil to the same skillet. Add the onions and bell pepper, if using, with a pinch of salt, and cook, stirring occasionally, for 12 to 15 minutes, until soft, golden, and jammy. Do not rush this step; it is where the flavor lives.
Add the garlic and cook for 1 minute, until fragrant.
Stir in the tomato paste and cook for 1 minute, then add the chopped tomato, vinegar, paprika, bay leaf, and white wine, if using. Simmer for 5 minutes, until slightly thickened.
Taste the sauce and adjust salt, pepper, or vinegar as needed.
Nestle the tuna steaks back into the skillet, spooning the onion sauce generously over the top. Simmer gently for 2 to 3 minutes, just to warm the tuna through without overcooking it.
Remove the bay leaf, scatter with fresh parsley, and serve immediately with rice, boiled potatoes, or crusty bread.