Larsson opener the scoring with a free-kick which evaded everyone and crept in at the far post and James McClean headed a second.
The Black Cats have now won four and drawn one of their last five games.
"Football is a funny game," Larsson said on ITV. "We seem to be doing things well at the moment and getting a little bit of luck when we need it.
"We want to carry on doing it."
McClean, 22, has impressed by scoring in his last two matches.
"I'm just enjoying my football, the manager's given me a chance," he said.
"I want to do well here."