Microwave the large potato for nine minutes. A medium potato needs seven minutes and a small potato needs five minutes. To add extra potatoes allow an extra four minutes for a large potato, three minutes for a medium potato and two minutes for a small potato. This is using a 1000w microwave – adjust for slightly longer or shorter if yours is a higher or lower power. Don't forget to pierce the potatoes with a fork a few times.
Chop the zucchini and bell pepper into small pieces and fry in oil for about six minutes.
While frying add the spices (or the fajita spice mix) and ⅛ cup water to the veg. Give it a good stir and add the corn for the last minute or so.
When ready, slice a deep groove through the middle of the potato in both directions. Repeat the process diagonally.