Add the meat in a large cooking pot and cover with 4 liters of water.
Bring to a boil over high heat.
Once it starts boiling reduce heat to medium-high.
Skim off any foam that forms on the surface.
Simmer for about 2-2,5 hours or until the meat feels soft when you prick it with a knife.
Remove meat from pot and transfer to a large pan setting it aside to cool.
Pass the stock through a sieve to remove any small bones.
Add the stock back to the pot. Note: The remaining stock should be about 3 liters if not add more water to it.
Season with salt, pepper, and bay leaf. Bring back to a boil.
Using a blender, blend the tomatoes until smooth and add to the pot.
Simmer over medium-high heat for about 15 minutes more
If using the spaghetti, cut it in smaller parts with your hands. To about 6-7 pieces. If using angel hair pasta, cut in half.
Add pasta to the pot and simmer until pasta is cooked as well.
Remove the bones from the meat, shred meat into small pieces and add to the pot.
Serve with crumbled feta cheese on top.