Tostadas de Ceviche

Step 1

Place the fish on a cutting board and cut it lengthwise, following the grain of the meat, into 0.5-inch-thick strips, then turn the strips 90 degrees and cut crosswise into 0.5-inch cubes—about the size of dice—so the pieces are roughly equal.

Step 2

Pour the lime juice into a medium glass or ceramic bowl (not metal, which reacts with acid), add the cubed fish, and stir once to coat all pieces evenly with the juice.

Step 3

Let the bowl sit at room temperature, uncovered, for 10 minutes. The fish will turn from translucent to opaque as the acid 'cooks' it—this is called curing.

Step 4

While the fish cures, cut the avocado in half lengthwise around the pit, twist the halves apart, and use a spoon to scoop the flesh into a small bowl. Mash it with a fork until it resembles chunky peanut butter, then season with a small pinch of salt.

Step 5

Drain the ceviche through a fine-mesh strainer, discarding the lime juice, and transfer the fish to a clean bowl. Stir in the chopped cilantro, then taste and add salt and pepper to adjust the seasoning.

Step 6

Arrange the 6 tostadas on two plates, side by side, placing 3 on each plate.

Step 7

Divide the mashed avocado equally and spread about 2 teaspoons on each tostada, creating a thin, even layer.

Step 8

Top each avocado-spread tostada with a spoonful of the cured fish ceviche, piling it slightly in the center, so each tostada has about 1.5 tablespoons of fish.