Blanch, peel, deseed and roughly dice tomatoes if you are using them.
Wash and finely slice the scallions and add to a large bowl.
Add salt, pepper, lime juice and chipotle or powder or chopped jalapeno. Muddle it so the flavours get to know each other.
Scoop out the avocado and start gently smashing it with a pestle or a fork.
Give it a taste and adjust as you wish. Zingier? Add more lime. Want it spicier? Add more chilli or chipotle. And so on.
Serve immediately. Preferably with some corn tortilla chips and a few wedges more lime. There's always that one person at the party that loves his guac extra zingy.
Notes
Store completely sealed off from air as it will go brown otherwise.
Consume within 2 days as the flavour will deteriorate and no one wants dodgy guac.
Can be frozen for up to 6 months.
Use freshly chopped chilli if you want it spicier.