The use of the word 'gravy' to mean a meat based red sauce seems to have originated with the New York Italian Americans (Correct me if I'm wrong!), who used the word to mean a long cooked, meat based tomato sauce, usually served on Sundays or special occasions. I've heard it referred to as 'Sunday gravy'. Perhaps Pongi can find an Italian 'root' recipe where it originated! Probably the abundance of meat here in the States as opposed to what was available in Italy, gave them the luxury of using all the different meats in this dish.
This is from 'The North End Italian Cookbook', by Marguerite Dimino Buonopane:
1 lb. sweet Italian sausage
2 lbs. meatballs, made up but not cooked
4-5 lean pork chops
1 lb. lean spareribs
1 lb. piece of beef or pork
1/2 cup olive oil
1 med. onion, chopped
1 garlic clove, chopped
pinch of dried basil, red pepper flakes, oregano, and mint
1 6-oz. can tomato paste
1 28-oz. can peeled, crushed tomatoes
1 28-oz. can water
salt/pepper
Brown the meats in 1/4 cup oil in a heavy saucepan, and transfer them to a platter. Add the remaining 1/4 cup of oil to the juices in the pan; when teh oil is hot, saute onion, garlic, and seasonings til transparent. Stir in tomato paste and blend well. Add tomatoes and stir til blended; stir in an extra 'pinch' of the seasonings. Add water til the sauce remains the thickness you desire.
Let the sauce come to a full boil, add salt/pepper and more herbs. Return the meat tot he pan, simmer over medium heat, uncovered, for at least 1 hour or til all the meat is fully cooked and fork tender. Stir gently every 15 minutes or so, to prevent the bottom burning.
Remove the meat from the sauce and place on a platter, cut in serving size portions. Skim the excess oil off the top of the 'gravy'. Serve the 'gravy' over your pasta of choice.
I learned a version of this when I lived in the 'Little Italy' section of Cambridge, Mass, way way back in the 60's
. The only addition was a piece of pepperoni, cut in bite size chunks, that was cooked along with the rest of the meat; it added a wonderful flavor to the sauce!