Palmdale or Lancaster after 10:00PM?
Ian, don't know if they're open that late but give this place a call:
Tom's No 26
1805 W Avenue J
We actually haven't eaten here ourselves (weren't too hungry yet), but stopped in during a road trip from Sequoia for a very yummy milkshake. The place has a lot of different food offerings (Mexican, American) and the prices were very reasonable.