Active Time

　　45 minutes

　　Total Time

　　1 hour

　　Roasted poblano chiles and cream are a classic—and irresistible—combination. It's worth roasting more than you need—the peeled and seeded chiles freeze well and thaw quickly. Sliced and seared zucchini or chayote squash is a terrific addition to the rajas mixture.

　　

Ingredients

Serves 8

　　

For the rajas:

10 poblano chiles

　　2 ears of corn, husked

　　2 tablespoons vegetable oil

　　1 large white onion, thinly sliced

　　1 teaspoon kosher salt, plus more to taste

　　1/4 cup crema (Mexican salted cream) or sour cream

　　

For the tostadas:

16 small corn tortillas or store-bought crispy tostada shells

　　Vegetable oil (for frying; if needed)

　　Kosher salt (if needed)

　　1 1/2 cups Creamy Black Bean Spread (optional)

　　Shredded iceberg lettuce, thinly sliced white onion, queso fresco, cilantro leaves with tender stems (for serving)

　　

Special Equipment

A candy or deep-fry thermometer

　　

Make the rajas:

Step 1

Preheat broiler. Arrange chiles in a single layer on a rimmed baking sheet. Broil, turning once, until blackened in spots, about 15 minutes. Transfer chiles to a large bowl, cover with plastic wrap, and let steam 15 minutes. Peel, seed, devein, and thinly slice chiles lengthwise.

　　

Step 2

Meanwhile, prepare a grill or grill pan for medium-high heat. Grill corn, turning occasionally, until kernels are tender and charred in spots, 15–20 minutes. Let cool, then cut kernels off cob.

　　

Step 3

Heat oil in a large skillet over medium. Add onion and cook, stirring occasionally, until light golden and tender, 10–12 minutes. Reduce heat to low, add chiles, corn, and 1 tsp. salt, and cook, stirring occasionally, until warmed through, about 2 minutes. Stir in crema and just heat through (do not bring to boil)-vegetables should be just coated; add more crema if needed. Season with salt.

　　

Assemble the tostadas:

Step 4

If frying tortillas, fit a large skillet with candy or deep-fry thermometer; pour in oil to measure 1". Heat over medium-high until thermometer registers 375°F. Fry tortillas in batches until crispy, turning every 30 seconds, about 2 minutes total. Drain on paper towel-lined baking sheets and season with salt.

　　

Step 5

Spread 1 Tbsp. Creamy Black Bean Spread, if using, on a tostada shell. Top with 1/4 cup rajas, then lettuce, onion, queso fresco, and cilantro. Repeat with remaining tostada shells. Serve at room temperature.

　　

Do Ahead

Step 6

Rajas can be chilled for up to 1 day. Reheat and let cool to room temperature before serving.