Drain chickpeas, reserving the liquid from the can and placing it in the freezer to rapidly chill down.
Remove the thin, diaphanous skins from the chickpeas either by gently squeezing each chickpea and popping it out of the skin, or by placing a clean kitchen towel or paper towel on a flat surface, laying the chickpeas in a single layer, and rubbing them gently with a second kitchen towel or paper towel.
Place peeled chickpeas into the blender or food processor and pulse until the chickpeas are puréed. The mixture will be thick and may require stopping the machine several times and scraping down the sides of the bowl.
Add the avocado, garlic, lemon juice, and salt, and pulse until the mixture moves smoothly in the bowl. Add the chilled liquid from the can from the freezer by the tablespoon to the food processor as it is running until the hummus is smooth and the consistency you prefer.
Taste, add more lemon juice and/or salt if needed.
Scrape the hummus into a serving bowl, drizzle with a few tablespoons of olive oil and garnish with chopped fresh herbs if using.