Yum Cha Chinatown is giving Friday afternoons a playful twist with Mahjong Social Fridays, pairing dim sum with a few rounds around the mahjong table. Cheryl Goh finds out what diners can expect, what’s on the menu, and how the homegrown brand is bringing a familiar social tradition into a new dining experience with Melody Tan, second-generation owner of Yum Cha.