Right next door is a very similarly named restaurant (Lac Thanh) which feels intentional. I sat down at the wrong place but realised before I ordered food so just had a (terrible) coffee before moving to Lạc Thiên. I had the Bánh khoái (their speciality) and bún thịt nướng (the peanut sauce version that seems quite common in this region). It was all ok.
"Mr Lac has been feeding travellers to Hue since the early 1990s and he continues to please. His deafness is no obstacle to communication. The local food is good and the family welcoming. A good lunch spot close by the citadel."
— From another review