Like others, I'd say look at the in-flight menu the week before you fly. You can also "book" an item from this in-flight menu so you are guaranteed to get it.
If nothing takes your fancy then book the cook. I have been both blown away and disappointed with the lobster, the latter being my most recent experience 2 years ago. I now book the cook: Fillet steak in green peppercorn sauce almost every time I fly. I've had it out of AMS, SIN, MEL, CDG and even Wellington (Thank you, JS!!)
It is the eye fillet, pink in the middle and goes well with the French red.
Lamb rogan is OK as is the lamb loin with jus/hipster, pony-tail gravy.
Mrs D couldn't be coughd with all this palaver and just chooses whatever is offered by the wonderful staff, her infrequent disappointment being tempered by a belly-full of French fizz.
When I'm feeling particularly adventurous I order the Asian choice for breakfast. Rice, chilli, hard boiled egg, peanuts and small dead fish is how I would describe it mostly. I'm sure the staff have a laugh at the assault on my Anglo palate but at least they give me genuine credit for "when in Rome".
Above all else; ENJOY !!