Dredge the beef cubes in flour, then fry in oil in a deep skillet until browned all over.
Meanwhile, toast the cumin seeds in a small dry (no oil) pan and then put them in a molcajete (mortar and pestle).
Toast the serrano chili in the same pan.
Add the garlic and black peppercorns to the cumin seeds and crush the mixture into a paste.
Stir in half a cup of water.
Add the garlic mixture and the water to the pot with the beef cubes.
Add the salt, oregano, paprika, onion, chili powder, cilantro, tomato, and serrano and cook for 3 or 4 minutes.
Add the broth and bring to a boil.
Reduce the heat and cover the pot, then cook on low for 1½ hours or until the meat is tender and the sauce has thickened.
Make sure you stir it every 20 minutes.
Serve hot.
Enjoy!