Remove the stems, seeds and veins from the chile pods. Rinse well. Place them in a pot and cover them with water. Place over medium-high heat and bring to a boil. Once the water starts to boil, reduce the heat and place a cover on the pot. Simmer for 20 minutes, turning the chiles over after 10 minutes to ensure they soften evenly.

Drain the chiles and allow them to cool.

Place the chiles in a blender along with the 1 1/2 cups water, flour, garlic and salt. Process until smooth. Strain the sauce through a fine sieve to remove the seeds and skin and discard. Season the sauce with more salt if needed.

Preheat the oven to 350F.

In a medium skillet, brown the ground beef, breaking it up as it cooks. add the garlic, salt and chili powder and continue to cook for another minute or two. Stir in the beans and cook for a few minutes to heat through. Remove from the heat.

To assemble the enchiladas, place 1/3 cup of the meat filling down the center of each tortilla; roll up. Arrange the enchiladas seam side down in a 9x13-inch baking dish. Pour the enchilada sauce over the top. Sprinkle the cheese on top, then bake until the cheese is melted and the enchiladas are heated through, about 25 minutes.

Serve topped with sliced green onions.