I've visited Delhi twice in the last three months, and while there I've discovered what is now one of my absolute favorite "dhabas". Rajinder Da Dhaba, while a little big for a traditional dhaba and often somewhat crowded, offers outstanding food. Located in Safdarjung, I would often order from them at 5pm (their opening time) and receive my delivery at AIIMS main campus by 5:30 or 5:45, which is a miracle on a Delhi weekday. My personal recommendations are every single appetizer on their menu, their chili paneer, alu kulcha/parantha, and their biriyanis. Like most dhabas, the biriyani is a little light on meat but the flavors are so excellent that it is well worth it, served in a clay pot and rich with butter and black pepper. If I could go back right now, I would buy Galauti Kabob, Achari Chicken, Malai Chicken, a veg biriyani, and two orders of alu kulcha.