Directions

1. Make the salsa: Preheat the broiler. Spread the tomatoes and serrano peppers on a foil-lined baking sheet and broil, turning occasionally, until charred, 10 to 15 minutes. Wrap in the foil and set aside, about 10 minutes. Rub off the charred skins; remove the pepper stems. Pulse the tomatoes, peppers, onion, garlic and 1/2 teaspoon salt in a food processor until chunky.
2. Heat the vegetable oil in a large cast-iron skillet over medium-high heat. Carefully add the tomato mixture and cook, stirring occasionally, until thickened, about 10 minutes. Stir in the cilantro and season with salt. Transfer the salsa to a bowl and cover to keep warm; wipe out the skillet.
3. Prepare the tortillas: Cook the bacon in a large nonstick skillet over medium heat, turning occasionally, until crisp, 9 to 11 minutes; drain on paper towels, reserving the drippings in the skillet. Finely chop the bacon. Combine all but about 1 tablespoon bacon, the masa harina and a pinch of salt in a medium bowl. Stir in 3/4 cup warm water and knead in the bowl until the dough is soft and pliable, about 2 minutes. Divide the dough into 4 pieces; roll each into a ball, then flatten into 4-inch disks.