Instructions: Peel potatoes and cut into 1/2-inch cubes. In a medium saucepan, bring 1 quart of salted water to a boil. Add potatoes, and simmer until tender, about 10 minutes. Drain, and set aside.

In a large skillet over medium heat, combine chorizo and onion. Cook, stirring often, until sausage is cooked through and onion is soft, about 10 minutes. If sausage has rendered more than a light coating of fat over bottom of skillet, pour off extra.

Add potatoes, and continue to cook over medium heat, stirring often, until potatoes begin to brown, about 8 minutes. As mixture cooks, mash everything together a little with back of a spoon or a spatula, scraping up any crusty bits of potato, so that it roughly holds together. Cover, and keep warm over very low heat.

Meanwhile, in a food processor fitted with the steel blade, combine tomatillos, garlic, and jalapeno. Pulse until fine. Add avocado, and pulse until combined. Season with salt.

Warm the tortillas as instructed below. Top each with potato mixture and avocado salsa, fold in half, and serve.

This recipe yields 12 tacos.

Comments: The secret to an authentic-tasting taco is the tortilla, the unleavened Mexican cornmeal bread that serves as its base. To get fresh-baked flavor from store-bought tortillas, chef Rick Bayless wraps them in a clean, damp kitchen towel and warms them for four minutes in a covered microwave-safe casserole dish. Then he lets them stand a few minutes before adding the potato-and-chorizo filling and avocado salsa.

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