1 teaspoon active dry yeast (from a 1/4-ounce package)
1 1/2 cups warm water (105-115°F), divided
1/2 tablespoon sugar
1 1/4 cups semolina flour
1 1/2 cups Italian "00" flour
2 teaspoons salt
1/3 cup extra-virgin olive oilEquipment: a stand mixer fitted with paddle attachment
Stir together yeast, 1/4 cup warm water, and sugar in bowl of mixer and let stand until foamy, about 5 minutes. (If mixture doesn't foam, start over with new yeast.)
Add semolina flour, "00" flour, and salt to yeast mixture along with oil and remaining 1 1/4 cups warm water and mix at low speed until a very soft dough forms. If necessary, mix in just enough "00" flour (up to 1/4 cup) to prevent dough from sticking to side of bowl. Increase speed to medium and beat, scraping down side of bowl occasionally, until smooth and elastic, about 5 minutes (dough will be soft). Scrape dough into center of bowl and dust with 2 tablespoons additional "00" flour. Cover bowl with plastic wrap and a kitchen towel and let dough rise in a draft-free place at warm room temperature until doubled, about 1 1/2 hours.
Preheat oven to 350°F with racks in upper and lower thirds. Line 2 large baking sheets with parchment paper.
Punch down dough and turn out onto a floured surface (do not knead), then cut dough in half. Keeping 1 half covered with plastic wrap, cut other half into 16 equal pieces and roll each into a 15- to 16-inch rope (1/8 to 1/4 inch thick), lightly dusting your hands if dough is sticky. Arrange ropes 1/2 inch apart on 1 baking sheet, then make more ropes with remaining dough and arrange on second baking sheet.
Bake, switching position of sheets halfway through baking, until grissini are pale golden and crisp, 30 to 35 minutes total. Transfer to racks to cool.