Step 1

Tenderize the Meat: In a medium bowl, combine the beef, baking soda, and salt. Mash with your hands until evenly combined and let sit on the counter for at least 20 minutes.

Step 2

Preheat the oven to 425°F and set an oven rack in the middle position.

Step 3

Make the Sauce: Heat the oil in a large nonstick skillet over medium-high heat. Add the meat and cook, breaking it up with a wooden spoon, until browned, about 5 minutes. Using a slotted spoon, transfer the browned meat to a plate.

Step 4

Add the onion, jalapeño pepper, and garlic to the skillet and cook, stirring frequently, until the onion is softened, 3 to 4 minutes. Do not brown; reduce the heat if necessary. Add the chili powder, cumin, oregano, and flour; cook, stirring constantly, for 1 minute more. Add the tomato sauce, then gradually pour in the chicken broth, stirring to combine. Add the beef and bring to a boil, then reduce the heat and vigorously simmer until the sauce is thickened, 12 to 14 minutes. Taste and adjust the seasoning, if necessary. (The sauce may taste a bit spicy; it will mellow out when combined with the cheese and tortillas.)

Step 5

When the sauce is almost done, soften the tortillas: Pour the oil into a small bowl or ramekin. Using a pastry brush, brush both sides of each tortilla with oil, then stack them on a plate and microwave, uncovered, until hot and steamy, about 1-1/2 minutes.

Step 6

Assemble the Enchiladas: Spoon about 1 cup of the sauce evenly into the bottom of a 13 x 9-inch baking dish.

Step 7

Put about 3 tablespoons of cheese and 2 generous tablespoons of the sauce onto the center of each tortilla, then roll the tortillas up and place them seam-side down in the pan, nestling each one against the last. (You'll have two rows of 5 enchiladas.) Spoon the remaining sauce over the rolled tortillas and sprinkle with the remaining cheese. (I like to sprinkle the cheese over the center of each row of enchiladas, rather than all over, so that the tortillas are partially exposed during baking.) Bake until the sauce bubbles and the cheese is melted, about 15 minutes.

Step 8

Make-Ahead Instructions: The enchiladas can be assembled up to one day ahead of time, tightly covered with foil, and refrigerated until ready to bake. The enchiladas may also be frozen for up to 3 months before baking (if frozen, defrost in the refrigerator overnight before cooking and allow a few extra minutes of baking time). The enchiladas can also be fully baked, tightly covered with foil, and refrigerated for up to two days or frozen for up to 3 months. To reheat: defrost if necessary and heat the covered casserole in a 350°F oven for about 30 minutes, or until hot in the center. If you'd rather reheat individual servings, small portions can be warmed up in the microwave for 1 to 2 minutes.

Step 9

Note: Always wear gloves and/or wash your hands very well after working with jalapeños, and keep your hands away from your eyes.

Step 10

Note: For maximum efficiency, prep the onion, jalapeño and garlic and measure out your ingredients while the beef tenderizes in step