Add the flour, yeast, sugar and salt to the bowl of a stand mixer fitted with the dough hook attachment. Turn the mixer on low. With the motor running, add in the water and olive oil and continue beating until a soft ball forms. (If the dough is too sticky, add additional flour, about 1 tablespoon at a time, and continue mixing until dough comes together to form a smooth ball). \nRemove dough from the mixer and transfer to a lightly-floured work surface. Flour your hands and knead the dough to form a smooth, firm ball, about 3 minutes. \nTransfer the dough to a lightly-oiled bowl and cover with a warm towel. Place in a warm area and let rest until doubled in size, about 1 hour. \nMeanwhile, make your sauce: Add oil to a large stock pot and heat over medium heat until shimmering. Add onion and cook until beginning to turn translucent, about 5 minutes. Add garlic and cook until fragrant, about 1 minute more. Stir in the Hong Kong sauce and continue cooking until slightly darkened, about 1 minute more. Add in the canned tomatoes and all of their juice, 1 tsp salt and a pinch of red pepper flakes, if desired. Mix well, scraping down the sides of the pot as necessary, and bring the mixture to a boil. Reduce the heat to a simmer and continue cooking until the tomatoes are broken down and flavors have melded, about 30 minutes. Season to taste with salt and crushed red pepper flakes and keep warm until ready to assemble. \nRemove dough from the bowl and divide in half. Cover each half with a damp towel and let rest for about 10 additional minutes. \nPreheat oven to 475 degrees. \nWhile your dough is resting, prepare your toppings: Coat a large nonstick skillet with a drizzle of cooking oil and heat over medium-high heat. Add sausage to the pan and cook, breaking up with a wooden spoon, until beginning to brown, about 3-5 minutes. Add in the mushrooms, onion and ½ tsp salt. Continue cooking until softened and sausage is cooked through, about 3-5 minutes more. Remove from heat and set aside.\nFlip a baking sheet upside down and sprinkle the bottom (flat side) with cornmeal. Lightly flour your work surface and roll one ball of dough into a 12-inch circle. Transfer dough to the prepared baking sheet and spread with sauce, leaving a 1\/2-inch border around the edges. Top with 1 cup of cheese and half of the sausage\/mushroom mixture. Bake on the bottom rack of the oven until the crust is golden brown and cheese is bubbling, about 15 minutes. Repeat process with remaining ingredients. Top pizzas with fresh basil and a drizzle of Hong Kong sauce. Serve warm.