Beat 1 large egg until well blended.
Pour into a small pan with oil.
Season with salt and pepper.
Using a small wooden spoon, fairly constant mixing to form a curd, raise the egg edges and tilt the pan to run raw egg below, until all of the egg is cooked.
Toast the slices of bread.
Mash the avocado and add some lemon juice.
Slice the tomatoes.
And assemble all as shown in the picture.