Prepare the Enchilada Sauce:
In a medium saucepan, combine tomato sauce, chicken broth, chili powder, garlic powder, onion powder, cumin, paprika, and salt.
Bring to a simmer over medium heat, stirring occasionally. Simmer for 10-15 minutes until slightly thickened. Set aside.
Cook the Vegetables:
In a large skillet, heat olive oil over medium heat. Add diced bell peppers, onions, and minced garlic. Sauté until vegetables are tender, about 5-7 minutes.
Add chopped spinach and cook until wilted. Season with cumin, chili powder, salt, and pepper.
Assemble the Enchiladas:
Preheat the oven to 375°F (190°C).
In a large mixing bowl, combine shredded chicken, black beans, sautéed vegetables, and 1 cup of enchilada sauce. Mix well.
Fill each whole wheat tortilla with the chicken and vegetable mixture, then roll tightly and place seam-side down in a baking dish.
Pour the remaining enchilada sauce over the rolled tortillas. Spread Greek yogurt over the top and sprinkle with shredded low-fat cheese.
Bake the Enchiladas:
Cover the baking dish with aluminum foil and bake in the preheated oven for 20 minutes.
Remove the foil and bake for an additional 10 minutes, or until the cheese is melted and bubbly.
Serve:
Let the enchiladas cool for a few minutes before serving. Garnish with fresh cilantro and lime wedges if desired.