To the food processor, add ¾ cup tahini, lemon juice, garlic, cumin, 1 heaping teaspoon kosher salt, and pepper to taste. Blend, and with the motor running, stream in the ice water, 1 tablespoon at a time. After 6 tablespoons of ice water, evaluate the texture. If you want it to be looser, stream in more water, and continue blending until smooth and creamy. Once you reach your desired texture, taste for seasonings, adding more salt, garlic, cumin, or lemon juice as needed.