Speaking afterwards, Elwood said: "The second half performance was fantastic. We had a chat at half-time and a few harsh words were said because we didn't turn up at all and we were playing second fiddle.
"We got some great scores in the second half though and played some good rugby. We're not as physically strong as some of the other teams so we try and get the ball away.
"This has been a while coming but we got the win and that's what was most important," he added.
To listen to an audio interview with the former Connacht and Ireland out-half, please click here.
To hear the thoughts of Ireland Under-20 scrum half Ian Porter, who was the man-of-the-match against Tonga, click here.
You can view match reports from Ireland's Junior World Championship games in our Ireland fixtures/results section.