In a food processor, pulse the walnuts until mostly crumbly, about 10 pulses. Add the mushrooms and pulse again until crumbly, but do not to overprocess.
3. Step
Heat the olive oil in a large saucepan over medium heat. Once the oil begins to shimmer, add the onion and cook for 3-4 minutes, until semi-translucent. Add the garlic and cook for another 2-3 minutes, until fragrant. Add the mushroom walnut mixture and cook for 5-7 minutes, until most of the liquid from the mushrooms has been released and evaporated. Add the soy sauce, paprika, fennel, salt, and pepper and cook for 3-4 minutes more, until the mushroom mixture begins crisp slightly. Remove from the heat.
4. Step
Use your hands to stretch the pizza dough into a circle about 14 inches (35 cm) in diameter and ½-inch (1 ¼ cm) thick. Lay on a sheet of parchment paper.
5. Step
Spread the marinara sauce over the pizza dough in an even layer, then sprinkle with the vegan mozzarella. Top with the mushroom walnut mixture, olives, and bell pepper.
6. Step
Bake for 14-16 minute, until the crust is lightly golden around the edges.
