Place the eggs in saucepan with cold water and bring to the boil. Boil the eggs for 8 minutes until hard. Plunge the eggs into cold water. Peel then slice the eggs.
In the meantime, cut the avocados all the way around the stone. Twist the two halves apart. Spoon out the stone. Scoop the flesh out of the skin with a spoon and slice into cubes.
Slice the cherry tomatoes into wedges. Mix the egg, avocado and cherry tomatoes in a bowl. Add the mayonnaise, yoghurt and mustard. Season with salt and pepper.
