The Republic of Ireland international was played in with a long ball from David Beckham and as he advanced towards Quakes keeper Jon Busch, he dummied at the last second and managed to round the gloveman to slot home much to the delight of the Galaxy fans.
Mike Magee put the finishing touches on the win in the final minute when he slotted home Sean Franklin's low cross from the right after San Jose had Steven Beitashour sent off nine minutes from time.
In Colorado, Chivas USA came from behind twice to eventually draw 2-2 with reigning champions the Rapids thanks to Angel's first goal for the club after joining from the Galaxy during the week.
The Colombian veteran ran on to a pinpoint pass from Nick LaBrocca to slide home a perfectly weighted shot from the top of the 'D' to make it 1-1 in the 36th minute.
Caleb Folan had earlier put the Rapids ahead and then Jeff Larentowicz made it 2-1 in the 69th minute before Laurent Courtois tied it up with four minutes remaining.
Elsewhere in North America, Dane Richards scored twice in the second half to allow New York Red Bulls to draw 2-2 with New England Revolution after Milton Caraglio's earlier double with both sides having a player each sent off in a dramatic match at the Gillette Stadium.
Columbus Crew defeated Philadelphia Union 2-1 on Ohio, Houston Dynamo got the better of Real Salt Lake with a 3-2 result, Seattle Sounders won 1-0 away at FC Dallas and Portland Timbers defeated Vancouver Whitecaps 2-1.
2011 MLS season - Week 23 scores