Combine the warm water, yeast, and sugar in the bowl of a stand mixer. Let the mixture stand for about 15 minutes, or until slightly foamy.
Stir in the olive oil, the 3 1/2 cups of flour, and the salt. Using the dough hook, knead on medium-low speed for about 10 minutes. The dough will be stiff, but add small amounts of water, about 1/2 teaspoon at a time, if necessary.
Gather the dough up into a ball and place in a large oiled bowl. Turn the dough to coat thoroughly with the oil. Cover the bowl with plastic wrap and let rise in a warm place for about an hour, or until doubled.
Heat the oven to 400F/200C. Line a baking sheet with parchment.
Fill a large, deep pan with the water . Stir in the baking soda. Bring to a boil.
Turn the dough out onto a lightly oiled surface and flatten slightly. Cut into 6 uniform pieces. Form each piece into a smooth ball, sealing at the bottom by pinching. Place on prepared pan. Let rolls rest for 15 minutes
Working with 3 rolls at a time, drop them into the boiling water/soda mixture. Boil 30 seconds one side then flip and boil 30 seconds on the other side. Remove with slotted spoon to prepared baking sheet. Repeat with remaining rolls.
Using a very sharp knife or razor blade, make 1/2-inch/1.25cm deep crosses on the top of the rolls.
Bake for 20-25 minutes or until rolls are a deep brown color.