Minnesota also scored through an own goal later in the second half, when Jan Gregus' free kick redirected off the back of San Jose's Harold Cummings.
The victory gives Minnesota back-to-back wins to open the season for the first time in the club's three-year MLS history. Both have come on the road, where the Loons play their first five before the opening of their new stadium, Allianz Field, on April 13.
Meanwhile, San Jose has lost twice at home to start 2019 and is winless in its last 10 games dating back to last season. Most of the Earthquakes' struggles have been defensive -- this was only their third scoreless game during their winless run.
Quintero now has two goals and three assists, having been involved in every Minnesota goal up until Saturday's late own goal.
He gave his team the lead in the 49th minute on a penalty awarded by referee Marcos de Oliveira following a video review.
Originally, de Oliveira allowed play to continue after ruling the ball had inadvertently struck San Jose defender Marcos Lopez's arm. Replays showed Lopez had leaned his arm into to the ball to block it as Ibarra had tried to play it past him, and thus, de Oliveira awarded the penalty.
Quintero stepped up, Earthquakes keeper Daniel Vega guessed to the shooter's left, and Quintero slotted a simple finish inside the right post.
Ibarra doubled the Loons' lead in the 52nd minute on a counterattack. After a San Jose attack faltered, the ball fell to Quintero, who pushed up field and then laid it off to Ibarra on his right. Ibarra cut to his left to evade a defender, then curled a left-footed shot beyond the outstretched Vega and inside the left post.
It became 3-0 in the 75th minute when Gregus' diagonal free kick from the right flank redirected off Cummings' back and then off the left post on its way across the goal line.
Minnesota pick up their 2nd win
Minnesota United shipped three goals past the San Jose Earthquakes at Avaya Stadium, to remain perfect after the first two games of the MLS season.