In a large bowl with an electric mixer cream butter and sugar until light and fluffy.
2 sticks unsalted butter, 1 cup light brown sugar
Add tahini and beat until combined well.
2/3 cup tahini
Beat in egg, vanilla, and salt.
1 1/2 tsp vanilla extract, 1 large eggs, 1/2 tsp Salt
Add flour and beat batter until just combined.
2 cups all-purpose flour
Beat in raisins and toasted sesame seeds.
1 cup raisins, 1/2 cup sesame seeds
Spread batter evenly in a buttered jelly-roll pan, 15 1/2 by 10 1/2 by 1 inch, and bake in middle of oven until a tester comes out clean, about 16 to 20 minutes.
Let cool in pan on a rack and cut into 36 bars.
Bars may be made 3 days in advance and kept in an airtight container