Gluten-Free Sesame Seed Hamburger Buns

Line cookie sheet with cooking parchment paper; spray paper with cooking spray (without flour). In small bowl, dissolve yeast in warm water; set aside.

In medium bowl, mix flours, xanthan gum, guar gum, cornstarch, salt and baking powder with whisk; set aside. In large bowl, beat eggs, sugar, oil and vinegar with electric mixer on medium speed. Beat in yeast mixture. Gradually add flour mixture, beating on medium speed until well blended (dough will be sticky).

Using 1/4-cup measure, drop dough into 6 portions onto cookie sheet. With wet hands, shape into buns, about 3 1/4x2 inches. Cover with plastic wrap; let rise in warm place about 1 hour 30 minutes or until doubled in size.

Heat oven to 350°F. Spread sesame seed in ungreased shallow pan. Bake uncovered 8 to 10 minutes, stirring occasionally, until golden brown. Set aside to cool. Remove plastic wrap from buns. Brush egg white over tops, being careful not to punch them down; sprinkle with toasted sesame seed.

Increase oven temperature to 375°F. Bake buns 15 minutes. Reduce oven temperature to 350°F. Cover buns with cooking parchment paper; bake 5 minutes longer or until instant-read thermometer inserted in center reads 207°F. Remove from cookie sheet to cooling rack; cool completely, about 1 hour. Split with serrated knife.