OnTriggerEnter smooth Rotate

Hello guys! I use this script for rotation my gameobject after every collision, but i dont understand how to make my rotatio smooth??

function OnTriggerEnter (other : Collider) {
        if (other.tag == "1FLTrigger"){
		transform.Rotate (0, -10, 0);
	}	
}

I’ve try also use this

transform.rotation =  Quaternion.Slerp (transform.rotation, Quaternion.Euler(0, 10, 0), 20.0);

But i can’t figure out how to correctly set Quaternion.Euler - i need, that after each collision it turn about 15 degrees( Thanks in advance!)

The answer provide her is good info. Quaternion.Slerp question, rotating back to original - Questions & Answers - Unity Discussions
the thing to note is that Slerp needs times to rotate to a position so you will need some condition to allow it to make is full rotation or you can simply use yield or coroutine and wait it out.