[C#] How to go about rotating a 2D object

I have a number of object with different rotation position and at a given time I want all objects to restore rotation to 0. I want that "return-rotation" to be animated meaning it should not happen instantly.

I am currently testing on a single object, tag = SK, but do not understand how to achieve this so it looks smooth.

I am currently testing on this code, not placed in Update():

Code (csharp):

1. float speed2 = 5;
2. float zRotation = 90.0f; // Just a test number to try to understand
3. dummyGameObject = GameObject.FindWithTag("SK");
4. dummyGameObject.transform.eulerAngles = new Vector3(dummyGameObject.transform.eulerAngles.x, dummyGameObject.transform.eulerAngles.y, zRotation * speed2 * Time.deltaTime);
5.  

I would appreciate any help on this topic as i do not really understand this fully.

 

I finally solved the basic problem with this piece of code:

Code (csharp):

1.  
2. if (isRotate) {
3.     dummyGameObject.transform.Rotate(0, 0, myRotationSpeed * Time.deltaTime * posOrNeg);       
4. }