A quick, green enchilada sauce made using items that you likely have on hand.
Heat oil in a large pan over medium heat. Once hot, add the minced onion and cook, stirring occasionally, for 5-7 minutes or until softened. Add the minced garlic and cook for 1 minute. Add the diced green chiles, oregano, and cayenne pepper (if using). Stir to combine and then add the flour. Stir continuously for 2 minutes and then slowly add the chicken broth (or veggie broth). As you slowly pour in the broth, stir the mixture to break up any flour clumps. Bring to a slow boil and then reduce to a simmer and cook for about 20 minutes, or until thickened. Make sure to stir the sauce every few minutes so that it doesn't stick to the sides. After the sauce has thickened, add the cilantro (if using). Taste the sauce and add salt, if desired. This recipe makes about 1 3/4 to 2 cups of green enchilada sauce.
I kept the sauce as is, but if you'd like a smooth sauce, then let the sauce cool slightly and blend it in batches. Be careful - hot liquids can expand when blending and create a dangerous scene.