I found a list of all HMS Storm's surface actions in uboat.net. The surface action I was talking about is the noted under the 23th July entry. Note the two escort ships sunk by the british submarine in that battle:
Also note that Lt. Young conducted an attack against one U-boat sent to resupply the monsun boats based at Penang (The action is described in the book, but it's not said that it was a german U-boat, I didn't know this)
12 Mar, 1944
HMS Storm (Lt. E.P. Young, DSC, RNVR) sinks a small Japanese vessel with gunfire in the Malacca Strait.
15 Apr, 1944
HMS Storm (Lt. E.P. Young, DSC, RNVR) torpedoes and sinks the Japanese minesweeper
W 7 (738 tons, offsite link) off the Andaman Islands in position 11º34'N, 93º08'E. (
see map)
18 Jun, 1944
HMS Storm (Lt. E.P. Young, DSC, RNVR) torpedoes and sinks the Japanese auxiliary gunboat
Eiko Maru (3011 BRT) in the Strait of Malacca off off Penang, Malaya in position 05.59N, 99.10E. (
see map)
20 Jun, 1944
HMS Storm (Lt. E.P. Young, DSC, RNVR) attacks the German submarine
U-1062 with torpedoes in the Malacca Strait. The torpedoes however miss their target. The u-boat had left Penang the previous day.
23 Jul, 1944
HMS Storm (Lt. E.P. Young, DSC, RNVR) sinks the Japanese army cargo ship Kiso Maru (554 BRT) and two Japanese patrol vessels with gunfire off Port Owen, Andaman Islands in position 14.00N, 96.50E. (see map)
1 Aug, 1944
HMS Storm (Lt. E.P. Young, DSC, RNVR) sinks 4 Japanese sailing vessels with gunfire of the Mergui Archipelago, Burma.
2 Sep, 1944
HMS Storm (Lt. E.P. Young, DSC, RNVR) sinks five small Japanese vessels with gunfire.
29 Oct, 1944
HMS Storm (Lt. E.P. Young, DSC, RNVR) sinks two Japanese sailing vessels with gunfire in the Gulf of Boni, Celebes, Netherlands East Indies
1 Nov, 1944
HMS Storm (Lt. E.P. Young, DSC, RNVR) sinks two Japanese sailing vessels with gunfire in the Gulf of Boni, Celebes, Netherlands East Indies.
2 Nov, 1944
HMS Storm (Lt. E.P. Young, DSC, RNVR) sinks seven Japanese sailing vessels with gunfire in the Gulf of Boni, Celebes, Netherlands East Indies.
http://uboat.net/allies/warships/ship/3450.html