Add the onions and garlic to the pan and cook, stirring constantly and scraping up the browned bits with a wooden spoon until softened, about 6 minutes.
Add the cumin and coriander and cook until fragrant, about 30 seconds.
Add the chopped chilies and reserved bean cooking/chili soaking liquid.
Bring to a simmer and cook until reduced by ⅓, about 10 minutes.
Stir in the cilantro and 1 tablespoon of lime juice.
The sauce should be relatively thick. If it is watery, allow it to reduce until there is no water pooling at the top of the pan.