In a large Dutch oven or pot over medium-high heat, heat the olive oil. Brown the beef (you may need to cut it in half and work in batches), about 3 minutes per side.
Set aside.
Reduce the heat to medium, and add the onion, garlic, and red and green bell peppers to the pot.
Stirring frequently, cook for 5 to 7 minutes, until tender.
Add the oregano and cumin, and cook for 1 minute more.
Add the sherry vinegar, and deglaze the pan, stirring up any browned bits from the bottom.
Cook for a couple of minutes, until most of the liquid has evaporated.
Add the broth and tomato paste, and stir well to combine. Throw in the bay leaves, and return the beef to the pot.
Season with salt and pepper.
Bring the whole thing to a simmer, reduce the heat to low, and cook for another hour.
Transfer the meat to a platter, and shred it. Return the meat to the stew, stir, and serve garnished with the cilantro.