Roasted green beans with mushrooms and peppers

1 lb. fresh green beans, rinsed and trimmed
1 red bell pepper, cut into strips
4 oz. button mushrooms, cleaned and quartered
salt and pepper to taste
2 T. oil
1 garlic clove, thinly sliced
1 T. fresh rosemary, chopped

Preheat oven to 400 degrees F. Toss all ingredients together and place on a baking sheet. Bake for 25 minutes.