Mitchell had Palace ahead before Emanuel Emegha and Samir el Mourabet struck for Strasbourg as they won 2-1 on Thursday night.
"It (scoring) is something that I've been trying to work on," Mitchell told TNT Sports. It's something that I think this season I got a bit better at, so I'm happy that I contributed, but unfortunately we didn't take away three points.
"It's disappointing. We created some decent chances. The two open goals were great chances.
"We just have to be more clinical. I think if we score that second goal, we then take away three points."
"We know in every game that we'll get chances. In every game, we believe we can win the match. So we step onto the pitch knowing that we can take away three points from any team, but today it didn't happen."