Bring a large pot of water to boil; season water with salt to taste (optional).
In a large skillet, gently saute chopped onions in olive oil for five minutes over medium heat.
Meanwhile dice the peppers into 1/2 inch squares, add to the skillet and saute for three minutes over medium heat. Season with salt, pepper and add the broth. Keep cooking until sauce is reduced.
Meanwhile cook pasta according to package directions, drain and toss with the sauce.