There's a lot about this cocktail that hits home. I live not far from that restaurant. Months ago, by recommendation from a liquor store near there, I bought Rey Campero. And I've long been a fan of the Cel Ray soda. Serendipitous as all this sounds, the drink fell a bit flat for me. Maybe not acidic/citrusy enough?? I'll play with the specs.
I went for it with a six-pack but well worth the expense. Not many years ago you had to go to Greece to buy pink grapefruit soda for a Paloma - then we shipped the first 3 pallets of Three Cents into the UK. Perhaps celery soda next!