Active Time

　　2 1D2 hr

　　Total Time

　　2 1D2 hr

　　It's the spicy, garlicky tomatillo salsa that really sells these addictive tostadas. Frying store-bought corn tortillas heightens the vibrancy of their corn flavor and creates a crisp foundation for the refried black beans, shredded romaine, lush avocado, and creamy queso fresco.

　　

Ingredients

Makes 6 to 8 (main course) servings

　　6 large garlic cloves, 4 cloves peeled and left whole and 2 cloves coarsely chopped

　　1 pound tomatillos (8 medium), husked, rinsed, and halved

　　4 fresh serrano chiles or 2 fresh jalapeños (including seeds), coarsely chopped

　　3/4 cup coarsely chopped fresh cilantro sprigs

　　2 cups plus 2 to 3 tablespoons water

　　1/2 cup finely chopped white onion, rinsed in a sieve and patted dry

　　1 3/4 teaspoons salt

　　2 dried avocado leaves (optional), coarse stems discarded

　　2 (15-ounce) cans black beans, rinsed and drained

　　3 tablespoons vegetable oil

　　2 (6- to 7-ounce) firm-ripe avocados

　　12 tostadas

　　3 cups thinly sliced romaine (from 1 head)

　　1 cup crumbled queso fresco (Mexican fresh cheese) or mild feta (1/4 pound)

　　

Make tomatillo sauce:

Step 1

Line a 10-inch heavy skillet (preferably cast-iron; not nonstick) with foil, then heat over moderately high heat until hot but not smoking. Add 2 whole garlic cloves and half of tomatillos, cut sides down, and roast on top of stove until well browned, 4 to 5 minutes (skillet will begin to smoke at this point). Turn over garlic and tomatillos (tomatillos may stick to foil) and roast until well browned and tomatillos are completely soft, 3 to 4 minutes. Transfer roasted garlic and tomatillos to a food processor. Discard foil, then line skillet with a fresh sheet of foil and roast remaining 2 whole garlic cloves and remaining tomatillos in same manner, transferring as done to food processor. Cool garlic and tomatillos to room temperature in bowl of processor, about 30 minutes.

　　

Step 2

Add chiles, half of cilantro, and 2 tablespoons water to mixture in processor, then pulse until it forms a chunky sauce, adding 1 tablespoon more water if too thick. Transfer to a bowl and stir in onion and 1 teaspoon salt.

　　

Step 3

If using avocado leaves, toast, 1 at a time, in a dry 10-inch heavy skillet (without foil lining) over moderate heat, turning every few seconds, until lightly browned and aromatic, about 1 minute, transferring to a plate as toasted. Bring beans and remaining 2 cups water to a simmer in a 3-quart heavy saucepan, stirring occasionally, then add avocado leaves and simmer, uncovered, stirring occasionally, 20 minutes. Drain beans in a sieve set over a bowl, reserving liquid. Pure beans, 1/4 cup cooking liquid (reserve remainder), avocado leaves (if using), and chopped garlic in a food processor until smooth.

　　

Step 4

Heat oil in a 10-inch heavy nonstick skillet over moderate heat until hot but not smoking, then add bean purée and cook, stirring, until very thick, about 5 minutes. Stir in remaining 3/4 teaspoon salt, then remove from heat and keep warm, covered.

　　

Step 5

Halve and pit avocados, then scoop out flesh in large pieces and cut into 1/2-inch cubes.

　　

Step 6

If necessary, stir some of reserved bean-cooking liquid in to make bean purée soft and easily spreadable. Divide warm beans among tostadas and spread evenly. Spoon about 1 tablespoon tomatillo sauce over each tostada, then divide avocado among tostadas and top with romaine, cheese, and remaining cilantro. Serve remaining tomatillo sauce on the side.