In a medium-size bowl, combine tahini with cold water and stir vigorously with a fork to soften for 2 to 3 minutes. Place chickpeas in a food processor and grind to a coarse meal. Add tahini, garlic, and cumin. Pulverize for about 45 seconds. Slowly add olive oil and lemon juice, alternating between each, and continue to process for about 5 minutes, on and off, until hummus becomes smooth and creamy. Season with salt and pepper.
Remove to a serving bowl and sprinkle with paprika. Garnish with parsley and a black olive.