Heat oil over medium heat in a large pan. Add in ground beef, onions, red pepper, green pepper and taco seasoning. Cook for about 10 minutes or until ground beef is browned.
Stir in tomatoes, salsa and green chilies and bring to a boil. Then cover and reduce heat to minimum and simmer for about 30 minutes.
While your sauce is simmering, cook the elbow macaroni in a large pot according to package directions. Drain the water and put back into the pot.
Add the sauce mixture to the macaroni and stir to combine. Mix in the cheese. Add green onions for garnish.