Pour the tahini and the lemon juice into your food processor, add salt and pulse to combine. Add 3 tbsp ice water and mix. Continue adding water until desired texture is reached (pourable but not watery). I love the tehini just like this, but if you want hummus...
Place garbanzos and 1.5 cups tahini sauce in food processor. Process at least 4 minutes to assure smooth consistency. Adjust seasoning. I like more tahini than this but not everyone does.
NOTE: I recommend to buy dry garbanzo beans and soak them overnight at room temperature with 1 tsp baking soda. Then cook until very soft. Alternatively use canned garbanzos.