I have a recipe for the Russian soup called ucha, but I'm not sure whether to make it. The problem is its source. I got it from Markus Wolf, who once ran the Stasi, a man who'd have the electrodes on you in a flash. We were talking in a cafe in the former East Berlin and he was in jolly form. I knew he had published a cookbook - bizarre, but then James Jesus Angleton of the CIA was a prize-winning orchid grower - and we got on to soup.
For ucha, certain principles were absolute. First, there had to be seven different fish for the boiling. Then it was strained and a second stock - he waved cheerily in the air to find the word - was produced with the addition of some better fish. And then there was a third process - he beamed contentedly at the thought - with the finest fish added. This was the Karla of East Berlin talking, the spider whose web of agents spread across the west (though there were, he claimed in passing, no "important ones" in Britain) and ensnared a German chancellor. He was the kingpin of a brutal and unforgiving security apparatus in the GDR. Should you eat this man's soup?
Wolf now portrays himself as an insistent voice for reform from within, pitted against a sullen leadership. He happily plays the part of an ordinary pensioner living in his apartment overlooking the River Spree, across which people swam to try to get away from him. He complains about the long flight of stairs, like any other old man. And he sparkles. "Give my regards to Gorbachev if you see him," he said ludicrously - chance would be a fine thing. "I wonder if he'll be pleased?"
I'll ponder the business of the soup. "The book is called Secrets of Russian Cooking," he said. "It has two meanings, you understand." Quite.
When I did see Gorbachev, he was sitting with Helmut Kohl and George Bush at a colloquy which was self-congratulatory, but compelling all the same. Kohl squeezed and stroked Gorby as if he was a cousin just back from abroad, and it was startling how the three old warhorses were determined to celebrate personal diplomacy as the secret of the peaceful revolution in Berlin. "We weren't a bad bunch," Gorbachev said. "I trust this man," Bush rasped, waving vaguely at both of them. Kohl beamed in the middle - like a huge panda who's just been allowed to mate - giving an extra slap of his thighs and giggling when Bush referred to "a friend in Downing Street" who had been unable to derail reunification. A most curious trio: none succeeded in office by an ally, yet all still patting Berlin like a baby.
And they were still able to call on the tricks of the trade. Bush was asked how he had reacted when the hotline disgorged Kohl's rushed ten-point plan for reunification. "Hell, I'm 75 years old. I can't remember what I had for lunch two days ago." Yet he still exhibited a certain preppie grit. Gorby and Kohl were happy to be kissed on both cheeks by that incorrigible old master of the smacker, Slava Rostropovich. So Bush stepped forward like a pro - though the last I heard it's not much done in Texas.
Now, pause a moment for Radio 4, and its expedition to celebrate the tenth anniversary of the fall of the Wall. Apart from Woman's Hour and Front Row getting under the skin of Berlin, and Today doing its stuff, the BBC debate brought the German foreign minister, the secretary- general of Nato and George Soros together in discussion. When will someone write the last letter to a newspaper about "dumbing down"? Not for a while, I suppose. But silliness has now become stupidity.
Of all the names that you'd expect to hear popping up in Berlin bars, John Selwyn Gummer wouldn't be at the top of your list. But there I was, trying to help a young German remember a name. He had a list of key words. Politics . . . hamburger . . . child . . . agriculture! The identification was complete. And, sure enough, at "Gummer" his face lit up. Now, this is unfair because we know that the celebrated "let them eat burger" photocall was a cock-up rather than paternal cruelty. But that picture certainly still has resonance.
I did try to fly the flag for beef, though I found myself floored by some incontrovertible facts from the past. The youth turned out to be something of a scientist, which you could say gave him an unfair advantage, but it was tough. Even songs of praise about various Scottish beasts of my acquaintance, fed on nothing but grass for generations, didn't stop him from predicting that it would be "15 years before we touch it". The only goodish news is that he says he doesn't fancy a visit to a French abattoir, either.
But there was a dark side to all this. Someone in the bar, a regular visitor to London, was bewildered by the prevalence of war films here. "Why can't you people forget?" A limp joke about how a film called Sink the Prince of Wales starring a Prussian Kenneth More wouldn't have packed German cinemas in the 1950s didn't put him off his stride. Could I convince him that we weren't still prey to easy prejudice? When an English friend chipped in to say that his half-German son was playing football in London and was told that he would want to be the referee because he was a German, I was weakening. And then someone mentioned A A Gill and his piece on Berlin. I left with as much dignity as I could muster, only to find "Lili Marlene" playing on the lullaby machine by my hotel bed. Berlin never lets you down.