What is bibimbap you ask? Well I'm glad you did, because you're going to want to run out to your closest Korean restaurant and try it out. Bibimbap is a bowl of rice with veggies, beef, and a raw egg cracked on top. The dish is served with a hot sauce that you pour over the top and then stir everything around. The hot food helps to cook the egg as you stir it around creating a kind of fried rice like dish.
What I love about Mandu is that I can get a Dolsot Bibimbap which means they serve my bibimbap in a hot stone bowl. This means that my rice is getting crispy on the bottom and it typically keeps everything a lot warmer for the entire time you're enjoying your meal. You also get a side of a collection of Korean appetizers, accompaniments to your meal like: kimchee, spicy zucchini, bean sprouts, and a potato/bean combo. The kimchee at Mandu is pretty good, not as spicy as I would have liked, but still delicious.
The restaurant is small, with a few tables outside so you can enjoy the weather when it's great. (It was really hot and muggy while I was in DC, so I sat inside with the AC.) The service is good, and the price is reasonable.
If you're going to be up near Dupont Circle in DC you should definitely check out Mandu. Get everything extra spicy, it'll clear your sinuses.