In a small/medium bowl add the water and sprinkle the yeast on top, let sit for 5 minutes, then stir. Add the flour and stir to combine. Cover with plastic wrap and let sit in a draft free warm area for about 2 hours or doubled.
In the bowl of the stand up mixer add the all purpose and bread flour (or semolina) and whisk to combine. Slowly add the water and mix with a fork, add the biga and knead with the dough hook for about 30 seconds, then add the salt, continue to knead for about 6-7 minutes to form a smooth dough. On a lightly floured flat surface form the dough into a ball in a lightly oiled bowl, rolling the dough to lightly cover in oil. Cover with plastic wrap and place in a warm, draft free area for about 2 hours until doubled in bulk.
Move the dough to a lightly floured flat surface and divide into 5 equal parts (about 70 grams each). Form into balls and with the round end of a wooden spoon poke a hole in each ball, gently stretch to enlarge the hole. Place on a parchment paper lined cookie sheet, cover with either plastic wrap or a clean tea towel and let rise in a warm, draft free area for about 1 - 1 1/2 hours. Before baking enlarge the holes again if needed.
Pre-heat oven to 400F (200C).
Bake for about 10-15 minutes until lightly golden, remove from the oven, lower the oven temperature to 340F (170C). Slice each roll in half through the middle and place cut side up back on the cookie sheet. Bake again for 30-35 minutes or until golden and hard, they should be dry. Remove to a wire rack to cool. Serve topped with the tomato filling.
In a medium bowl add all the ingredients and toss together.
If you find the friselle too hard for your teeth, you can soften them up my drizzle with a teaspoon or two of water before adding the tomato topping.