Sieve the flour in a large bowl, add the salt, butter, olive oil, water and yeast and knead by hand for 10 minutes (or if you have a standing mixer, mix on first speed for 3 minutes, then at the second speed for another 4-5 minutes).
Cover the mixing bowl with a cloth, and let it rest in a warm place for one hour. At this time, you can turn on the oven, and preheat it at 190 degrees Celsius.
When the dough has doubled its size, move it to a lightly floured surface and cut it into small portions of 30-35 grams each. Cover with plastic foil and leave it to rest for 10-15 minutes.
Roll or strech each piece, trying to keep an even dimension along the length, to aprox 20 cm. Before transfering to baking sheets, roll the individual bread sticks into fine semolina - this adds a plus of texture to the grissini.
Bake at 190 degrees Celsius for 20 minutes or until golden brown.
Leave the grissini to cool comletely before serving. I can say that they are even crispier the next day. Sore them into an airtight container for up to 5 days.
To serve, dip the grissini in good quality extravirgin olive oil.