Fixing the kitchen sink

In the process of helping my wife cook for a grand lunch today (Surasamharam ), the sink protested refusing to even allow a drop of water to trickle down. Both of us patiently watched the pool of water hoping that by some miracle the water level would reduce slowly. But that was not the case. So, I knew it was time to get down and dirty. The good thing is that the pipe assembly below is easy to figure out and can be unscrewed easily without any wrench etc. So, unscrewed the U-tube from the steel part and wonder'o wonders, the pipe was filled with thick black material (probably accumulations of several months of use before we came in). Quickly let some steaming water to pass through the tube and the pipe was clear. Fixed the assembly back again and gushing water passed through in no time. Got to go back now.....to continue the grand lunch....more details later.