But in a remarkable finale, Sale fought back to collect two points as their hosts switched off following a 10-minute injury break.
Quins won their fifth straight game - their best start to a season since 1996 - and therefore remain top of the table.
They took the lead after just two minutes when Sam Smith's break on the right caught Sale drifting, and despite a strong tackle by Will Addison, Smith managed to throw a pass in-field which Mike Brown took in his stride and scored.
Evans kicked the conversion, and the Premiership leaders doubled their lead five minutes later.
Charlie Matthews won a lineout, Karl Dickson sparked the backline and following a slick succession of phases, George Lowe crashed over close to the posts. Evans again converted, leaving Sale staring up a steep hill on a hot afternoon.
A 12th-minute penalty by fly-half Nick Macleod put the visitors on the scoreboard, but within minutes they had to do some serious tidying in their own 22 as Harlequins swarmed back on the offensive.
The pressure told,
referee Martin Fox spotted a visitor standing up in the scrum and the deadly Evans rifled over the resultant penalty.
But when careless hands in midfield gifted Sale possession on 24 minutes, Sam Tuitupou ran at the heart of the home defence, drew two challengers and delivered a perfect offload to Rob Miller who sprinted clear for a try between the posts, Macleod converting.
Evans experienced his first miss from the tee when a long-range penalty attempt drifted wide at the last second, further encouragement for Sale whose fightback from a desperate start was impressive.
But Sale were then floored by three tries in six minutes.
With 33 minutes on the clock, Quins stormed the walls yet again and it was popular lock, Ollie Kohn, who celebrated his 100th appearance for the club by battering his way over the line.
Before Sale could draw breath, Quins were all over their defence again and Brown was on the end of the pass thrown out by Dickson.
When panic descended upon the visiting rearguard, prop Mark Lambert crossed the line, backed by his pack for Harlequins' fifth try - and Evans converted all three.
Dwayne Peel capitalised on a mix-up in communication on the stroke of half-time, crossing on the right with half the Quins players static as if they had heard a whistle. Macleod converted.
Peel's period as hero ended four minutes into the second half when he fumbled the ball under pressure, recovered to throw a pass only for Evans to intercept and sprint for his team's sixth try, which he duly converted before making way for Rory Clegg to a standing ovation.
Yet the visitors sensed the possibility of a try-bonus point in a game where Quins were more concerned with scoring than defending, and edged closer to that reality when the speedy Miller ran in his second-try, scooting clear from half-way and Macleod converting.
The game was held up for nearly 10 minutes when Will Addison was injured making a tackle and was carried from the field on a stretcher.
Sale's bonus-point try duty followed when a succession of phases led to a penalty for offside, and Vadim Cobilas went over in the corner, Miller converting.
Further tries by Vadim Cobilas and Joaquin Tuculet meant Sale did not go home empty handed from a 12-try thriller.
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