Cornbread Stuffing with Sweet Peppers, Onions, and Celery

1 red bell pepper , diced

1 yellow bell pepper , diced

1 orange bell pepper , diced (or any combination of above bell peppers)

1 1/2 medium onions , minced

3 stalk(s) celery , diced

1 cup(s) chicken or turkey stock

6 fresh sage leaves , thinly sliced

2 tablespoon(s) fresh marjoram or oregano , minced

2 teaspoon(s) salt

3/4 teaspoon(s) freshly ground pepper

8 cup(s) cornbread , diced into 1/2-inch cubes