One-pot steak and pasta casserole

1 T olive oil
1 lb. lean sirloin steak, cut into 1/2" cubes
1 onion chopped
1 red bell pepper seeded and chopped
1 green bell pepper seeded and chopped
1 28 oz.can of chopped tomatoes (I used italian tomatoes w/garlic, basil and oregano)
2 T tomato paste
2 cloves of garlic crushed
3 C reduced sodium beef broth (divided)
4 celery stalks, sliced
8 oz. of fusilli pasta (I used whole wheat)
1 1/2 C button mushrooms
1 t dried oregano or 1 T chopped fresh oregano
coarse ground black pepper

Heat the olive oil in large Dutch oven, brown the meat, remove with slotted spoon. Add onions and peppers to the pot, stirring often  until soft (about 5 minutes) Add the tomatoes with their juice, the paste, garlic and 2 cups of the broth. Stir well and bring to a boil.
Return the beef to the pan and the celery and season w/ pepper. Cover and simmer gently until the beef is tender (about an hour).
Add the pasta, oregano, mushrooms (cut the buttons in half if they are large) and add remaining broth. Bring the mixture to a simmer,  reduce heat and cover the pan.  Cook until the pasta is tender.  (about 20 minutes) Serve immediately.

The recipe said it serves 4..but it looks like it will feed 6.  It was quite yummy!