The tuna for this recipe must be sashimi grade as only the edges will be thoroughly cooked. Sashimi-grade tuna is difficult to find unless you patronize a premium fishmonger or even better, a Japanese fish market, which typically carries it. (If you don’t have either in your area, ask at your local sushi bar if they would sell you sashimi tuna. I’ve bought fish that way.) To be sashimi grade, the tuna not only must be amazingly fresh, but it must be cut from the bottom of the loin, where there is no connective tissue. It should be free of any visible lines (no semicircles within the flesh) or blood, with even color. Its limited supply has made it very costly. The tuna for this filling is quickly seared, a technique known as tataki in Japanese cooking. With each mouthful, you enjoy the delicious contrast between the spicy-smoky seared crust of seasonings and the cool raw center of the tuna. Cucumbers add a nice crunch, as does a garnish of colorful sliced radishes.

　　

Ingredients

makes 8 tacos

　　1 cup red chile powder (page 151)

　　1/4 cup chipotle chile powder (page 151)

　　1/4 cup fine sea salt

　　1/4 cup cumin seed, toasted and ground (page 164)

　　2 tablespoons coriander seed, toasted and ground (page 164)

　　2 tablespoons dried Mexican oregano, toasted and ground (page 161)

　　2 tablespoons black pepper

　　1 1/4 pounds sashimi-grade tuna, cut into 2 1/2 by 1 1/2 by 4-inch pieces

　　1 tablespoon vegetable oil

　　3/4 large English cucumber, peeled, halved lengthwise, and sliced crosswise into 1/4-inch-thick half-moons (about 1 cup)

　　1 tablespoon lemon-infused olive oil (page 162)

　　1/4 teaspoon sugar

　　1 tablespoon grated lemon zest

　　1/4 teaspoon kosher salt

　　8 (5 1/2-inch) crispy yellow corn tortilla shells (page 17), for serving

　　Garnish: Iceberg Lettuce Garnish (page 144) or sliced radishes

　　

Step 1

In a large bowl, mix together the red and chipotle chile powders, sea salt, cumin, coriander, oregano, and black pepper. Toss the tuna pieces in the seasoning mix.

　　

Step 2

In a large, heavy, nonstick skillet, heat the vegetable oil on high heat. Sear the tuna pieces all around, 1 minute per side. Remove from the heat and slice the tuna into 1/4-inch-thick slices.

　　

Step 3

In a bowl, mix the tuna with the cucumber, olive oil, sugar, lemon zest, and salt. Serve immediately. The filling will keep up to 2 hours in the refrigerator.

　　

Step 4

To serve, place some shredded lettuce in each crispy shell, divide the filling equally between them, top with salsa and garnish, and arrange in a taco holder. Or, lean the filled shells in a row, propped upright, on a platter. Eat right away. To build your own, place some lettuce, then filling, in a crispy shell, top with salsa and garnish, and eat right away.

　　Tacos by Mark Miller with Benjamin Hargett and Jane Horn. Copyright © 2009 by Mark Miller with Benjamin Hargett and Jane Horn. Published by Ten Speed Press, an imprint of the Crown Publishing Group, a division of Random House, Inc.Mark Miller is the acclaimed chef-founder of Coyote Cafe in Santa Fe, New Mexico. He has started and owned thirteen different restaurants on three continents from 1979 to 2008. He is the author of ten books with nearly 1 million copies in print, including Tacos, The Great Chile Book, The Great Salsa Book, and Coyote Cafe. Mark currently works in International Culinary Consulting and lives in Santa Fe, New Mexico.Benjamin Hargett is a travel-loving chef who has cooked in Europe, the Carribean, Mexico, and the United States, where he worked with Mark Miller at the Coyote Café for many years.