Reserve about a third of the beans. Mash the rest of the beans in a medium bowl with a large fork. Set aside.
Heat the oil in a medium skillet over medium-high heat. Add the onion, and cook until lightly browned, about 4 minutes. Add the garlic and continue to cook, stirring, until lightly browned. Add the spices and cook until fragrant about 1 minute.
Add the mashed beans and half the broth; cook, stirring frequently, until slightly thickened, about 5 minutes.
Add the reserved beans and the enough of the remaining broth to loosen up the beans. Simmer until the beans are thick but not pasty, about 2 minutes more.
Season with salt and pepper to taste. Stir in the fresh coriander, if desired, and serve.