Preheat the oven to 325°. Lightly oil a cookie sheet.
Mix together the brown sugar and butter, and beat until they are creamy. Stir in the egg, vanilla extract, and lemon juice. Add flour, baking powder, salt, and sesame seeds. Drop by rounded teaspoons onto the cookie sheet 2 inches apart.
Bake for 15 minutes or until the edges are browned.