I emailed the restaurant on the off chance of getting a booking, lucky for us they were having an extra dinner on the Saturday night - which turned out to be the biggest rainfall in Beijing for 60 years. Luckily Black Sesame Kitchen was very near where we were staying so after wading through water ankle deep then knee deep we got to the restaurant. Unfortuantely we had to sit in the room off from the kitchen as at the time it was too wet at the tables next to the kitchen! The chef did an excellent job especially in the circumstances. Great 10 courses but the highlights were the dumplings, the spicy chicken and the signature dish - Black Sesame Icecream with candied battered bananas. With as much beer and wine as you want 300RMB is reasonably good value. Is definitely a must if in Beijing but book in advance.
As it is quite hard to find - look out for the Tatoo place and the entrance is beside it - you have to wind your way through some alley ways!!