There are a lot of mines in chapter 2 and several opportunities to do this. When fighting a mech near mines, position yourself so the mech's back is to the mines. Then use the Wide Swing (A+X) to knock it back. Keep knocking it back until it enters the mine area and explodes (harmless to you, and the mine doesn't go away). If fighting multiple mechs, repeat for fun, profit and easy victory.
Below is a video.