Heat olive oil, then add chiles and onion; cook until they begin
to soften, but do not allow them to brown.
Add remaining ingredients
except for water or broth and cook, stirring frequently, for 1/2
hour over very low heat.
Add just enough broth or water to make the sauce a little soupy
and continue cooking an additional 10 minutes. The sauce should
be thick enough to coat a spoon without immediately running off,
so add more liquid or cook a while longer, as necessary.
Yields enough to serve 4 with chips or with a meal.