Preheat oven to 350 degrees and line a baking sheet with parchment or lightly grease it.
Cream together butter and sugar in a stand mixer.
Add in tahini. Remove seeds from the vanilla bean and add those to the mixture (or extract).
In a separate bowl mix together flour, baking powder and salt. Add the flour mixture in by spindling it over the wet mixture with the mixer on low speed. Mix just until incorporated. Roll the cookie batter into 1 tablespoonful balls and place 1 inch apart on the prepared baking sheet.
Bake for 8-10 minutes or until starting to slightly crack on top.
You can find tahini in most grocery stores and at all health food stores. Tahini is a ground up sesame seed paste.