Sorbete de limon al mar de cava

My contribution to DOTMC last year was inspired by this dessert, Sorbete de limon al mar de cava, which I first had in January 2008 at Cal Boter in Barcelona. I was lucky enough to be able to return yesterday and couldn't resist ordering it again, even though the menu has other tremendously delicious and classic Catalan desserts. There is something about this perfectly smooth sweet and sour sorbet floating in an equally sour but very strong liqueur that just gets my goat. The other thing that makes me crazy is the liqueur is basically impossible to find, even here in Barcelona, so I guess I'll just take what I can get and enjoy the special chances I have every few years.