Drain the beans.
In a large Dutch oven, heat the oil over medium heat until shimmering.
Add the onion and 1 teaspoon salt, then cook, stirring occasionally, until it begins to brown, about 5 minutes.
Stir in the garlic and cilantro stems. Cook, stirring, until fragrant, about 30 seconds.
Stir in the beans and broth, then bring to a boil over medium-high.
Cover, reduce to low and cook, stirring occasionally, until the beans are tender, about 1 hour.