Smash the avocado in a bowl and add the lime juice, salt and pepper and stir.
Spread on the toast
Top with toppings of choice
Notes
To store unused halves of avocado, wrap it tightly with plastic wrap and place in fridge - it will be good until the next day. Don't worry if it goes a little brown, as you can just scrape that bit off and you will be left with bright green avocado.
If you don't like your avocado mashed up, or you just can't be bothered, you could slice it instead.
Add a kick of heat to all of these with a sprinkle of red chilli flakes.