Servings: Makes 12
Ingredients 12 extra-large jalapenos (with stems)3 cups (about 3/4 pound) grated mozzarella cheese2 quarts canola oil2 cups masa harina1 to 2 tsp. chipotle chili powder , to taste (optional)1 1/2 tsp. kosher salt , plus more to taste1/2 cup all-purpose flour
Note: Masa harina, a type of corn flour used to make traditional dishes like tortillas and tamales, is available in grocery stores and Mexican markets. When working with jalapeños, be careful not to touch your face; if you have sensitive skin, you may want to wear plastic gloves.
Place a rack in the oven about 8 inches from the heat source; preheat broiler. Arrange jalapeños on a baking sheet and broil, turning occasionally, until charred and softened but still somewhat firm, 7 to 8 minutes. The jalapeños can also be roasted over the open flame of a gas stove burner. Transfer to a heatproof bowl, cover tightly with plastic wrap, and set aside for 10 minutes.
Working carefully, use a paring knife to scrape off and discard as much jalapeño skin as possible. Make a cut down 1 side of each jalapeño and remove ribs and seeds with a small spoon, being careful not to tear peppers further. To fill each jalapeño, firmly press together 1/4 cup cheese in the palm of your hand to form an oblong mass, then stuff inside jalapeño; set aside.
Pour oil into a large pot and heat over medium-high until oil registers 375° on a deep-fry thermometer. Meanwhile, in a large bowl, whisk together masa harina, chili powder, 1 1/2 teaspoons salt, and 2 3/4 cups water. Put flour in a wide, shallow dish.
Working in batches, roll jalapeños in flour, shaking off excess; then hold each by the stem and dredge in batter to coat completely. Carefully drop jalapeños into hot oil by their stems and fry, turning occasionally, until deep golden brown, 4 to 5 minutes. Transfer to a paper-towel-lined plate, season with salt to taste, and serve warm.