Cook the beef in a pot with boiling water, with one onoin cut in rings, one laurel leaf and the beef-tea cube until it's soft.
Take out the meat from the water and let it cool down, then shred the beef with the hands.
Heat-up the oil and fry the onion and the mortar garlic. Add the paprika cut in strips, the tomatoes cut in block, sweet paprika, the salt and pepper ( the result of this is called sofrito).
Cook this around 10 min.
Reserve the half of the sofrito in a bowl.
To the other half of the sofrito add the beef and a little of the water where you cooked the beef in.
Cook that around 15 min, it must stay juicy.
Heat-up the black beans and add the other half of the sofrito which you reserved, mix this good.
Peel the plantains, cut them in slices and fry them in warm oil.
Serve everything with white rice.