Combine semolina, all-purpose flour, and salt on the counter and form a mound with a well. Add lukewarm water a few tablespoons at a time, mixing until the dough absorbs water without turning sticky.
Clean the work surface of loose flour, then knead about 8 minutes until smooth and elastic.
Wrap the dough in plastic wrap and rest about 15 minutes.
Pull off a lemon-sized piece and keep the rest wrapped. Roll it into a rope about 1/2 inch (1.3 cm) thick. Slice into very thin disks (about 1/16 inch if possible). Press each disk with a rotary thumb motion to form a shallow cup about 1 inch (2.5 cm) wide. Repeat with remaining dough.
If not using immediately, dry on clean towels, turning occasionally. When fully dry (about 24 hours), store in a box in a cupboard for a month or more.