Quintero and the Loons also enjoyed a successful run in the 2019 U.S. Open Cup. Quintero made his first appearance of the tournament on June 12, scoring twice and added an assist as Minnesota defeated Sporting Kansas City 4–1. In the Round of 16, Quintero scored twice to help the Loons recover from a two-goal deficit and defeat the Houston Dynamo 3–2. He scored again in the quarterfinals, helping Minnesota advance past New Mexico United by a score of 6–1. Quintero would score his sixth goal in his fourth Open Cup game of the season to help the Loons defeat the Portland Timbers 2–1 and advance to the first US Open Cup final in club history. He would begin the final on the bench, coming on in the second half. However Quintero was unable to rescue the Loons as they fell to Atlanta United 2–1. Quintero's six goals saw him win the Open Cup Golden boot. He was also named as the Player of the Tournament, the first time the award had gone to a player who failed to win the cup in over a decade.