Start by cutting the avocados in half and removing the seeds. Place the flesh of 1/2 (half) avocado in a blender and dice 1 avocado. Use the remaining 1.5 avocados in another recipe (perhaps mango avocado salsa?).
In a large mixing bowl combine the diced avocado with the shrimp, corn, onion, jalapeno and lime zest.
To make the sauce blend together the avocado half, garlic, cilantro, lime juice, water and mayonnaise until smooth. Season to taste and pour over the filling ingredients.
Stir gently until well combined. Adjust the seasoning and spoon the mixture into the 6 avocado shells. Sprinkle a little cayenne (if using) over the top and chill your shrimp stuffed avocados for 30 minutes before serving if possible.
Use medium/large shrimp or king prawns.
Zest the lime before juicing it.
You can prepare the filling ingredients up to 3 hours ahead (keep them refrigerated, covered). Stir in the sauce just before serving.
Chill for 30 minutes before serving if possible. Consume within 3 hours. Keep refrigerated, covered.