In a large stock pot, melt butter and sauté chilies, onion, celery, pepper, leeks, garlic, and oregano over moderate low heat until softened—about 15 minutes.
Gradually add the flour cooking over low heat until the mixture is golden—about 15 minutes.
Gradually stir in the chicken broth.
In a blender, puree 1 ¼ c. of the corn.
Add corn and remaining ingredients.
Cook until heated through.