Do you mean zap a zap? Or reply with a kind 1 note?
Either way it would technically be an "e" tag with a marker of "root" but I don't think any clients would show it
You would be better off copying the zaps ID and embedding it in a note with nostr: 

 Thanks! That's actually what would be ideal: 
Embed the zap in a reply to my own post that got the zap.

Where can I copy the event Id's of those zaps?  

 I don't know if there is a client that will show that, yet
I can easily add it to noStrudel though 

 https://cdn.satellite.earth/ff2ee224d46d28022b6009da771e93746d7fc6f1243b6f2f012adb31bf4f7576.png
⚡ 149K if I can have this haha.

💯  necessary for #V4V in my book.  

 Its not quite a reply but maybe this will work.
Although it displays kind of funny in other clients right now
http://cdn.hzrd149.com/644ee3f3c0329683e5b72d3bbdde2253bd39bcf63bc1e86c3a1a922a4dec1e72.png 

 Aaaaaawesome! 
I can use that copied embed code to do my thing. 👌

Thank you man. 

 Just something to be aware of, if you quote a zap it won't notify the person who zapped since the "zap" event is created by the LN node
So you may have to @ mention them to get the notification 

 Ah damn, yup that's great to know. Sucks a bit tho. 

Cashu zaps don't have this problem right?  

 That's cool!