Preheat grill to medium, scoop out flesh of avocado. Rub avocado, bell peppers, jalapeño, green onion with a little olive oil. Grill all, turning occasionally, until there are scorch marks and a little softened
Add the grilled veggies, lime juice, parsley, and salt to a food processor and process until smooth (or slightly chunky if you wish). Add more lime juice if necessary
Transfer gazpacho to a container and chill for at least 30 minutes. Serve chilled in bowls and garnish with pistachio.