Defrost the avocado cubes at ambient temperature. Once defrosted, crush them with a fork until they have a creamy consistency. Finely chop the onion, add it to the avocado, then add the chilli pepper, oil and the tomato cut into small cubes. Grate the lime peel and squeeze the juice adding it to the mixture and complete with salt and pepper. Mix everything and let it rest for an hour in the fridge. The guacamole is now ready to taste, perfect especially with tortillas for a yummy aperitif.