Crush half of an avocado with a drop of lemon juice, salt and pepper. Set aside.
Cook a scrambled egg in a small saucepan with a teaspoon of vegetable oil. Season with salt and pepper. Set aside.
Wash and peel the cucumber and the carrot. Slice 4 thin pieces of cucumber, keep the rest in a cool place. Slice the carrot into thin slices lengthwise. Set aside.
In a bowl, mix the yogurt with some lemon juice, salt and pepper.
Start assembling the sandwich: on a slice of bread, spread the crushed avocado. On the other slice, spread the yoghurt/lemon mixture. Add the scrambled egg, cucumber and carrot slices and the salad leaves on top.
Close the sandwich and cut it in two pieces before you bite!