Chicken Enchiladas | Black Bean Enchiladas

Preheat the oven to 350°F (176°C). Line a baking dish with aluminum foil.
In a medium bowl, combine the mustard (if using), oil, chile powder, and salt. Add the chicken and toss to coat. Place the chicken in the baking dish and bake until just cooked through, about 30 minutes.
Let the chicken cool slightly and then shred the breasts using 2 forks or your fingers. Set the meat aside along with the juices from the baking dish.

Add just enough olive oil to a large nonstick or cast-iron skillet to coat the surface and place it over medium heat. Sauté the onion until softened, 5 to 8 minutes.
Add the zucchini and continue to sauté, stirring occasionally, until the zucchini is tender and browned, another 6 minutes or so.
Add the garlic, beans, chile powder, cumin, and salt, and cook until the beans are tender and the garlic is fragrant, about 5 minutes. Remove from the heat.

Melt the butter in a large skillet over medium heat. Add the garlic and jalapeños and cook until softened but not yet beginning to brown, about 4 minutes.
Add the flour and cook for 1 minute, stirring constantly. Still stirring constantly, add the stock in a slow, steady stream. Increase the heat to medium-high and bring the mixture to a boil. Then reduce the heat and simmer until the liquid has reduced and the sauce has become opaque, about 5 minutes. Remove from the heat and let it cool slightly.
Transfer the sauce to a blender or food processor, add the sour cream, chiles, cumin, chile powder, salt, and cayenne, and purée until smooth. (If you don’t have a food processor, mince the chiles by hand and then whisk all the ingredients into the skillet).

Coat the bottoms of two 9-by-13-inch baking dishes with some of the green chile sauce.
Place the tortillas on your work surface. Top 8 tortillas with the chicken mixture and 8 with the black bean and zucchini mixture, spooning the mixture along the center of each tortilla. Sprinkle each with some cheese and cilantro.
Roll the tortillas over the filling and place the filled tortillas, seam side down, in the baking dishes. (You can assemble the enchiladas–all of ’em–ahead of time and stash them in the fridge prior to warming them. Cover and refrigerate the green chile sauce separately.)
Pour the remaining green chile sauce evenly over the enchiladas and sprinkle with the remaining cheese. Bake the enchiladas for 30 minutes, or until the sauce is bubbling and the cheese is beginning to brown.
Garnish with the extra cilantro and scallions and serve with the lime wedges. (A word to the wise: You can stash the leftovers in the fridge and sneak them out of the house in the morning to take to work with you for lunch. You’re welcome.)