Add tahini, cold water, olive oil, cumin, salt, garlic and lemon juice to a food processor. Puree until smooth.
Add in the chickpeas. Puree for 3-4 minutes, pausing halfway to scrape down the sides of the bowl, until the hummus is smooth. If it seems too thick, add in another tablespoon or two of water.
Taste and season with additional salt, cumin, and/or lemon juice if needed.
Serve immediately, garnished with your desired toppings. Or transfer to a sealed container and refrigerate for up to 3 days.