Peel, pit and roughly chop the avocado. Place in a food processor with the lemon juice and blend until the mixture is smooth. Add the yogurt, spices and sea salt and pulse the processor a few times to mix. Transfer the guacamole to a bowl and carefully stir in half of the chopped green pepper, reserving the remainder to sprinkle on top of the mixture as decoration. Guacamole can be served as a salad on a bed of tortilla chips or as a dip for crudites such as celery and carrots.