Making his first start since May 12, the Dodgers' top prospect gave up one hit over three scoreless innings as Class A Advanced Rancho Cucamonga defeated Lake Elsinore, 8-3.
Lee struck out four without issuing a walk and said the groin was not an issue at any point.
"I threw pretty well," he said. "I located my fastball pretty well and got ahead of batters early in the count, which made it a lot easier on me in the long run.
"Health-wise, it felt good. I had no problems coming back to it early on. Warming up, I was trying to stretch it but not too far. In the game, I let natural ability take over and had no problems."
Four pitchers finished off the Quakes' fourth win in five games, allowing three runs on eight hits. Jordan Roberts (1-0) earned the win by striking out three over three scoreless frames.
Michael Pericht carried Rancho Cucamonga offensively, going 4-for-4 with two homers, a double and six RBIs. On the season, he's hitting .326 with eight longballs and 22 RBIs in 25 games.
"He's really improving," Lee said. "He's found a little more comfort at the plate this year compared to last year, even though at end of last year I thought he was swinging the bat pretty well. He works really hard and has great dedication to game."
Lee, selected 28th overall in the 2010 Draft, injured his groin three or four days after his previous start. He started to feel better later in the week, but the organization decided to play it safe and put him on the disabled list.
"I was sitting and moved my legs up, and I kind of readjusted myself and felt a little tightness in my groin," Lee explained. "From there, it never really loosened up. I don't really know exactly what caused it."
Lee said the treatment he received was pretty basic: Rest, ice and working out the tightness. He pitched a few times at extended spring training before rejoining the Quakes for his start against the Storm.
"I threw a couple bullpens and threw in a simulated game on Monday before I came back here," he said.
The 20-year-old right-hander came into Friday's game with a 5.13 ERA over 40 1/3 innings, but his outing lowered that mark to 4.78. In his next few starts, he'll try to build his stamina back up as if it were Spring Training.
"We're just trying to extend it a little bit further each time out, assuming everything goes well," he said.