1. Make the sauce: Heat a medium saucepan over medium heat. Add the olive oil and tomato paste. Cook, stirring frequently until paste just begins to darken, about 3-4 minutes. Add the spices and mix with the paste and the oil. Pour a small amount of broth into the paste and stir to incorporate. Continue adding small amounts of broth and stirring until all the broth is added and the paste is fully incorporated. Tear one corn tortilla into small pieces and add it to the sauce. Add the sugar and bring to a simmer. Cook, stirring occasionally for about 5 minutes. Remove from the heat, add the vinegar, and blend in a blender or with an immersion blender until smooth. Set aside.
2. Make the filling and assemble the enchiladas: Preheat the oven to 350°. Heat a large sauté pan over medium heat. Add the olive oil and onions and cook, stirring occasionally until the onions are soft, about 5 minutes. Add the black beans, green chilis, and salt and pepper to taste. Stir well to combine and turn off the heat.
3. Pour 1/3 cup of sauce into the bottom of a 9”x13” baking dish. Use a spoon to spread the sauce and cover the bottom. Use five tortillas to cover the bottom, breaking two in half to fill the space. Pour a little over a ½ cup of the sauce on top of the tortillas and again spread it around to cover. Distribute half of the bean mixture over the sauced tortillas and sprinkle with a cup of cheese. Repeat with tortillas, sauce, bean mix, and cheese. Cover the top with the remaining five tortillas, then the remaining sauce and the remaining cheese. Cover with foil and place in preheated oven. Bake for 20 minutes. Remove the foil and bake another 5-10 minutes, or until the filling is hot and bubbly and the cheese is melted.   
4. While the enchiladas are baking, prepare the toppings and cook the vegetables. Once the toppings are prepped, heat a large skillet over medium heat. Once hot add the olive oil, onions, zucchini, and peppers (if using fresh) and toss to combine. Cook, stirring occasionally until the vegetables are just starting to soften, about 5 minutes. Sprinkle with cumin, oregano, and salt and pepper to taste; if using frozen peppers add them now. Increase the temperature to medium-high and continue to cook for another 5 minutes, or until the vegetables are done to your liking.
5. Serve slices of enchilada with a side of veggies and have everyone add their desired toppings. 

Source: Heather Pratt

Tips for What to Do With Excess Ingredients: Leftover tomato paste can be frozen in 1 tablespoon dollops on a sheet of parchment until solid and then transferred to a ziptop freezer bag and stored for 2-3 months. It is measured and ready to add to any recipe calling for tomato paste.