No, you can’t take one steak.
Aside from it being just really strange (and tight), think about it practically.
At most BBQs, it’s the blokes on the grill. Not always, but often. They’re standing around, chatting, rotating the meat, and paying superficial attention. the BBQ is full of food getting cooked - your solitary steak will be fairly lost in the melee.
As things cook, they get up ready for serving.
How are you going to manage it at his point?
Will you have been hovering over the chef, keeping an eye on your steak?
Will you elbow everyone else out of the way, to claim your steak?
What if someone gets to it first, and helps themselves to it?
Will you confront them?? 
Just take maybe 4 steaks - you don’t have to take one for everyone, as that’s not how it works. People don’t have one of everything.
If you take, say, four - chances are you’ll be able to have one, without any of the above hilariously embarrassing scenarios needing to take place.