Preheat oven to 350 degrees F. In a large bowl beat butter with an electric mixer on medium to high speed for 30 seconds. Add the granulated sugar and salt. Using the tip of a small sharp knife, scrape out seeds from vanilla bean. Discard pod or reserve for another use. Add vanilla seeds to sugar mixture. Beat until combined, scraping side of bowl occasionally. Beat in cornmeal and cornstarch until combined. Gradually add flour, beating on low speed until mixture starts to cling. Form mixture into a ball. Divide dough in half.
On a lightly floured surface, roll each portion of dough into an 8-inch circle. Place circles on an ungreased large cookie sheet. Cut each circle into 12 wedges, leaving wedges in circle. Prick wedges with a fork. Using the fork, press a decorative edge into wide end of each wedge. If desired, sprinkle with sanding sugar.
Bake about 15 minutes or just until edges start to brown. While still warm, cut into wedges again. Cool on cookie sheet for 5 minutes. Transfer wedges to wire racks; cool.