My first thought upon entering Beaker & Flask (727 SE Washington St., 235-8180, beakerandflask.com): “Huh. So this is what we’ve been waiting for.” The belated opening of Kevin Ludwig’s high-concept cocktail bar has been a running joke in the local restaurant scene for years now—the coasters read, “Established 2007 2008 2009”—but the elegant lounge at the end of Sandy Boulevard is worth the wait. A long, concrete bar adorned with aquamarine glass tiles commands attention, curving through the center of the high-ceilinged, bullet-shaped room. Behind it a wall of high shelves, packed with bottles of spirits, cocktail hardware and plain glass jars of mysterious tinctures, shows that Ludwig and his company of top-notch bartenders aren’t fooling around here. Customers in expensive jeans sit along the bar and in the enormous semicircular leather booths that line the curving streetfront window, sipping complex concoctions of unusual spirits with names like Sandy Shandy, Coltrane! Coltrane! Coltrane! and Joe McCarthy’s Ghost, for which they pay $7 to $9 apiece (beer is $5). For those who prefer a solid diet, Benjamin Bettinger prepares non-bar-food bar food: octopus, sweetbreads and squash blossoms ($6-$22).