Restaurants lacking a hard liquor license have been slaking the thirsts of Cocktail Nation by mixing up drinks based on one low-proof spirit or another, with questionable results. (A rice-wine martini isn't, you know, a martini.) The RoHan Lounge, a sleek, moody, red and black nightspot in the Richmond District, employs as its alt-alc of choice soju, a Korean tipple somewhere between sake and vodka in inebriant intensity. The results are impressive, possibly because soju, distilled from rice, barley, or even sweet potatoes, assumes so many different characteristics that it can complement several varieties of cocktail or be drunk alone as an aperitif. RoHan serves seven premium sojus and mixes them into cocktails — like the Ming, a combo of soju, grapefruit juice, a touch of lime, and a float of Campari — that stand on their own as worthy examples of the mixologist's art.