Tostadas de Atún o Trucha (Tuna or Trout Tostadas)

Tostadas de Atún o Trucha (Tuna or Trout Tostadas)
Marcus Nilsson © 2019

My tuna tostada is composed of layers: a smoky chipotle mayonnaise spread over the shell, topped with slices of silky tuna, briefly marinated in ponzu, capped with a scattering of crispy fried leeks and a single perfect slice of avocado. The success of this dish depends on choosing top-quality fish, of course. At Contramar, we only serve it when sustainable tuna is available, so it’s not always on the menu. In San Francisco, I’ve substituted a locally farmed trout, although the rest of the recipe is unchanged. You can also make these with hamachi, kampachi, or albacore. But in my opinion, raw tuna and trout are especially beautiful for their deep pink color. Whatever fish you use, make sure that it’s sashimi-grade and slice it as thinly as possible against the grain.

For the fried tostada shell, it’s ideal to have stale corn tortillas because fresh tortillas curl up in the fryer. In Mexico, you always see people drying out their old tortillas, either to feed to the pigs and chickens or to use in chilaquiles and tostadas. If you know you are going to want to make these tostadas for a party, then plan ahead and leave your tortillas out for a day or two first. Place them in a single layer on a baking sheet with another baking sheet on top of it to keep them flat as they dry out. If you go the extra step of first making tortillas from scratch solely for the purpose of making tostadas, be sure that they’re quite thin: no more than 1⁄8 inch / 3mm thick. A thicker tortilla will be difficult to get crisp in the fryer.

This is finger food, so I like my tostadas to be fairly small. To make smaller (than 6-inch/ 15cm) ones, simply, cut your tortillas in half and then fry them.


  • 1 thick leek, white part only, thoroughly washed and sliced into 1⁄8-inch / 3mm-thick rounds
  • 2 cups / 480ml rice bran oil, safflower oil, or any vegetable oil with a high smoke point
  • 8 stale corn tortillas
  • 12 oz / 340g sashimi-grade tuna, trout, or other fatty fish, thinly sliced against the grain
  • 1 Tbsp olive oil
  • ¼ cup / 60ml soy sauce
  • ¼ cup / 60ml freshly squeezed orange juice
  • 2 Tbsp plus 2 tsp Mayonesa con Chipotle (page 62)
  • 1 avocado, cut in half, pitted, peeled, and cut into 8 to 16 slices
  • Maldon sea salt or another finishing salt
  • Lime wedges


  1. First, place the leeks in a bowl of cold water and separate the rings. Remove any green rings and reserve these for making stock. Transfer the white rings to a dish towel to dry out for at least 15 minutes so that they’re completely dry before frying.
  2. Meanwhile, warm the rice bran or safflower oil in a large heavy-bottom saucepan or deep skillet over medium-high heat (you want the oil to be at least 2 inches / 5cm deep) to 350°F / 180°C. You can test the temperature with an instant-read thermometer or by submerging a wooden spoon in the oil, which will be immediately surrounded by little bubbles if the oil is at the right temperature.
  3. Line a plate with a brown paper bag. Fry the tortillas one at a time, for about 2 minutes each. While the tortilla is frying, use a pair of chopsticks or two forks to hold down the two edges so that the tortilla doesn’t curl up. Once the tortilla is golden, remove it from the oil and let it drain on the plate. Repeat with the rest of the tortillas and let them all cool for at least 15 minutes while you prepare the rest of the ingredients. You want the tortillas fully cool or else the mayonnaise will melt.
  4. Using the same oil in which you fried your tortillas, fry the leeks: Decrease the oil temperature slightly to 300°F / 150°C. Check the temperature with an instant-read thermometer before adding the leeks; if the oil is too hot, the leeks will turn dark and become bitter. Drop in the leeks and constantly move them around while they fry so they cook and color evenly. The instant you see the leeks turning golden, remove them with a slotted spoon and set them on the plate to cool completely.
  5. While the tostadas and leeks are cooling, marinate the fish: Place the fish in a bowl and drizzle it with the olive oil so that the citrus and soy sauce don’t bite into the fish and give it a gray cast. After lightly coating the fish with olive oil, immediately add the soy sauce and orange juice, toss, and let sit for 5 minutes.
  6. Once the tortillas are cool, spread 1 tsp of the mayonnaise on each one. That may seem like very little, but you don’t want it to be thick and ooze out from under the rest of the toppings. On top of the mayonnaise, distribute the sliced fish in one layer. Scatter with the fried leeks and top with the avocado. Just before serving, add a pinch of the finishing salt.
  7. I like to serve these tostadas 4 per plate, to be passed around, with lime wedges on the side.

Reprinted with permission from My Mexico City Kitchen: Recipes and Convictions by Gabriela Cámara and Malena Watrous, copyright © 2019. Published by Lorena Jones Books, an imprint of Penguin Random House.

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