Scoop the flesh out of the avocados and put it into a bowl. Add a little lemon juice and mash it with a fork.
Add the sweet corn, the crumbled feta and the crab sticks, cut into pieces, and mix so that all the ingredients blend together. Season with a touch of olive oil and salt and stir well.
Fill the avocado halves with the mixture and garnish with a sprinkling of Parmesan cheese (optional).