Combine the first 5 ingredients in a small saucepan. Cover and cook for 5 minutes on medium. Continue cooking for 2 minutes uncovered to evaporate excess water. Remove from heat and cool.
Cut avocado in half and remove pit. Cut avocado into 1/2 inch cubes. (Do this by making 1/2 inch spaced cuts in the avocado crosswise and lengthwise. Be sure not to cut into the skin of the avocado. Then use a spoon to scoop the flesh out.)
Put the avocado cubes in a medium bowl. Add lime juice and stir gently. Chop the bell pepper and add to the bowl. Add cooked corn and red onion to the bowl. Gently stir and serve.
This salad is best eaten on the day it is made because the avocado tends to darken by the next day.