In a small bowl, combine the lemon juice and water.
In a separate bowl (or a measuring cup), whisk together the tahini paste and olive oil until thoroughly incorporated.
Reserve 2 tablespoons of chickpeas as a garnish.
Place the rest of the chickpeas in a food processor and process them for 15 seconds. Add lemon juice and water mixture, garlic, cumin, cayenne pepper, black pepper, and salt. Process until mixed, scraping down the bowl as necessary, 50-60 seconds.
While the food processor is running, slowly (in a steady stream), pour the tahini paste and olive oil mixture from the tube, and process until smooth and creamy (or it reaches your desired consistency,) for 30-40 seconds.
Transfer the hummus to a plate and sprinkle it with chopped parsley and reserved chickpeas. If preferred, drizzle it with olive oil. Serve it with pita chips or toasted bread on the side.