For the pizza dough: Mix together the flours and yeast in a large bowl, then pour in the water and mix together, squeezing with your fingers to thoroughly hydrate all the flour, until it has formed a shaggy mass. Cover the bowl in plastic wrap and set aside until the dough looks relaxed and somewhat smooth and the flour is completely hydrated, about 1 hour.
Add the salt and squeeze the dough with your hands to incorporate. Turn the dough out on a counter and knead until the gluten develops and the dough is beginning to show some resistance, about 10 minutes. Spray a bowl with cooking spray or lightly coat with oil, then add the dough and cover with plastic wrap. Allow to rise overnight in your refrigerator.
Turn the dough out onto a counter and divide into 4 portions as evenly as possible. Take each portion and imagine them as a square; start by folding opposite corners into the middle until you've done all four corners. Repeat the process, then fold the dough over itself in half, turn 90 degrees and fold again, tucking the seam side down. Grip the dough ball like a doorknob and pull it towards you while turning it clockwise to seal the bottom. Place on an oiled sheet pan and repeat with remaining dough portions. Cover with plastic wrap and allow to proof at room temperature for 2 hours.
For the pizza sauce: Put a pizza stone in your oven and turn the heat as high as it will go. While the oven is preheating, place the red onion on the pizza stone and allow it to roast until the skin has turned black and the onion feels slightly soft to the touch, about 45 minutes to 1 hour. Remove from the oven, allow to cool enough to handle and peel back the first couple layers to reveal the roasted onion inside. Cut into quarters, then separate into individual petals.
Combine the canned tomatoes with the olive oil and sea salt in a small bowl and crush it all together with your hands. (Crush it as coarse or as smooth as you'd like, it's your pizza.)
Cook the Italian sausage off in a frying pan over medium-high heat, breaking up with a spoon, and cooking all the way through. Drain off the grease and allow to cool.
When the oven and pizza stone are both well preheated, at least an hour or so, begin to stretch your pies. Carefully remove one dough ball from the sheet pan and toss it into a bowl of flour. Lightly press it down with your hand to flatten it, applying even pressure. Pick the dough up by your fingertips about 1/2 inch in from the edge, and with your fingertips turned inwards, slowly start to rotate the dough in a circle to form a crust. Once you've completed a full circle, set the dough down on the counter. Using your fingertips, dimple the inside of the crust edge to flatten it down. Then pick it up, and resting the dough over the back of your hands, start to rotate the dough, allowing it to stretch with its own weight, moving your hands as if you were making a U-turn in a car. Once the dough is stretched to 10 to 12 inches, place it on a well-floured pizza peel.
Spread some of your pizza sauce evenly around the dough with a spoon, keeping it inside the crust. Crumble a quarter of the cooked sausage over the top, then place 6 to 8 of the roasted onion petals over that. Tear the mozz into tablespoon-size chunks and place them on top of the pizza (each pie should get about 3 ounces). Large chunks around the outside, smaller in the middle, but none in the center, or it will make your slices hard to pick up.
Place the pie in the oven on the pizza stone with a quick jerking motion, then quickly shut the door. Cook the pizza until the crust is almost a dark walnut color, 10 to 15 minutes. Don't be scared of some char; the closer you can get to being burnt, without actually burning the pizza, the better.
Remove the pizza from the oven, sprinkle with the flaky sea salt, drizzle with olive oil, and cut into slices. Repeat with the remaining ingredients to make 3 more pizzas.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.