For the dough: Whisk together 1/4 cup of the flour, 1/4 cup of the water and the yeast until smooth with no lumps to create a sponge. Cover with cling film and leave in a warm place for 20 minutes. Add the remaining flour, water, the oil, milk and salt and transfer to a mixer fitted with a dough hook. Mix the dough on low speed for 10 minutes, and then place into a lightly-oiled bowl and cover with cling film. Let proof for 2 hours at room temperature, or let rise in the refrigerator overnight. (If you are refrigerating the dough, remove 30 minutes before using to come to room temperature.)
Preheat the oven with a pizza stone on a lower rack to 500 degrees F.
For the clams: Combine the clams, wine, shallots and garlic in a medium pan. Cook over high heat until the clams pop open, 3 minutes. Drain the clams in a colander set over a bowl to catch the liquid. Pick the meat from the clams, placing the meat in a small bowl. Strain the reserved juice over the clams.
For the pizza: Pulse the tomatoes and salt together in a food processor to a chunky consistency. Remove the dough from the bowl, keeping it as round as possible, and coat it completely with 00 flour. Stretch into a 12-inch circle, and transfer to a pizza peel.
Top the pizza with the tomato sauce, garlic, parsley, clams (without juice), chili oil, soppressata and pecorino cheese. Bake for 6 minutes.