Dal Bukhara from ITC Maurya is the best but yes, it leans towards expensive side. But I also totally love the one served by Moti Mahal Deluxe (Malcha Road), Lazeez Affair and Gulati.
You can also try it from The Treat, Chanakyapuri..Kake da hotel, Gulati, pandara road and last but not d least Bukahra @Itc maurya new delhi it's expensive but the most tempting one in city.