*Disclaimer - This only works if you like coffee and smoking.
It's all in the planning.
Enter Macro, go straight to the lamb and get a lump of off the bone shoulder. The frozen shoulder is around 2.XXkg, so costs near on 400 baht.
Take lamb to the man and say you want it cut into steak slices. The man cuts and bags it for you.
This is where the magic happens.
As the lamb is cut, it starts to defrost more quickly. I go around and do my shopping, pay for the goods, pack the car up (I have a cool box for my frozen goods), but leave the lamb in the footwell of the car whilst I go and have a coffee attached to my Macro.
After my coffee, I retrieve the lamb and with my stamped receipt, enter Macro again with my half defrosted lamb and ask the bemused man behind at the meat counter to now mince the same cut of meat he sliced an hour before.
Sounds like a ball ache, but it's quite easy if you're planning to have a coffee and smoke after shopping.