Iron is one of the more reactive metals, which is why traditional wisdom is not to cook tomatoes and other acidic foods in cast iron, since they can pick up a metallic flavor. In our experience, this isn't an issue if the pan is well seasoned.
Oregano is Greek for "joy of the mountain." Greek oregano has a milder flavor than the Mexican variety usually found in the spice aisle of your supermarket. Look for Greek oregano at Italian or Greek markets.