In the Middle East, tahini is just a paste of oil and lightly toasted sesame seeds. With a good food processor or blender it's a snap to make, and it will keep for a month or so in the fridge. We like to make a big batch to have on hand for impromptu hummus production.
about 2 cups
2 cups white sesame seeds
1/4 cup olive oil
Heat a heavy wide-bottomed sauté pan over medium-high heat. Add the sesame seeds and toast lightly - about 2 minutes, shaking the pan so they toast evenly. Let cool completely.
Put in a food processor and drizzle in the olive oil. Pulse for 3-5 minutes, or until it's as smooth as you can get it. Add a little more olive oil if necessary. Refrigerate.