I can see connoisseurs fixing the mixture to meet their own expectations ~ with bread crumbs, pieces of cheese, olive chunks ~ all in there, ready to go just like the good old days. They show up to dine, have the maître'd take their bottle out of storage, and set it on the table. The rest is up to the customer!
No doubt this will be confusing to everyone but Souvrn'rs on vacation.
There are times when I bring my own Johnney’s Seasoning Salt to put on my reastaurant steak. I can see someone having their own vinegar and oil flask in a pocket ready to use for a restaurant dinner.