Software update?
Had the same problem. Used the youtube clips referenced elsewhere in this forum and cleaned the EGR valve thoroughly.
However, this was not enough as well as long ru s (multiple).
Ended up taking it to Lexus. Came back a new car, response was as new. Consumption was great and of course no smoke even in very cold weather (<= 0) - which is when it predominantly manifested itself.
From Lexus I was informed that they (re)cleaned the EGR, did a Software Update, and since no other faults were found, that was all they did for this issue.
Note that, my driving routes are mainly city driving which is not ideal for diesels. Also i've had the car for 11years now and I don't think the egr and onwards had ever been cleaned :(
I would take it to Lexus, worth the trouble imho.