You can, but only for short periods of time, such as a quick sauté.  And, the pan should be washed and seasoned immediately afterward. Acidic ingredients like tomatoes can strip seasoning on your skillet, erode the surface of the pan, and can lead to a metallic taste in your food.  Long simmered tomatoes, like making a tomato jam or sauce, are best made in a non-reactive sauce pan, such as stainless steel.