Steps for preparation

Preheat the oven to 350 °F.
Line two cookie sheets with parchment paper or, if you prefer, get them ready without greasing them.
In a large heavy skillet over medium heat, toast sesame seeds until golden brown, shaking the skillet and stirring frequently to avoid burning or browning them too fast. Remove from heat and set aside.
Mix the flour, sugar, butter, water, baking powder, vanilla, salt, and egg in a large mixing bowl. With the help of an electric mixer on low speed, beat the ingredients until well blended, occasionally scraping the sides of the bowl with a silicone spatula.
Gently fold 1/2 cup of the sesame seeds into the dough until all ingredients are well combined.
Using about 2 teaspoons of dough for each cookie, shape into ovals of about 2 inches in length. Work with all of the dough and roll each cookie in the remaining toasted sesame seeds.
Place the rolled cookies about 1 inch apart from each other on the prepared baking sheets.
Bake in the preheated oven for about 15 to 20 minutes, or until lightly browned.
Remove the cookies to wire racks to cool. Store the cookies in a tightly covered container for up to 1 week.