For the dough: In a medium bowl, mix the yeast with warm water and let sit for 5 minutes. Add 2 tablespoons olive oil, sugar and salt, and whisk. Set aside. In a large bowl, mix the plain and whole wheat flours. Make a hole in the middle and pour in the yeast mixture. Slowly hand mix the flour until all the liquid is absorbed. If too wet, add more flour, 1/4 cup at a time. Sprinkle a clean work station with flour and knead the dough until smooth and elastic. Coat a large ceramic bowl with the remaining olive oil. Place the dough in the ceramic bowl, and flip over to coat in the oil. Cover the top of the dough with plastic wrap and cover the bowl with a dish towel. Let rise until the dough has doubled in size, 2 hours.
Punch down the dough and let rise for another hour.
For the toppings: Using a mandolin, slice the potatoes and onion. Roughly chop the rosemary leaves. Preheat the oven to 220°C. Grease the pizza pan with the leaf lard. Mold the dough into the shape of the pan. Brush with some olive oil. Place the pizza on the bottom oven rack for 5 minutes, to pre-crisp the crust. Add two layers of the potatoes in a scallop style. Add the onions, sprinkle with salt and pepper and drizzle with some olive oil. Sprinkle with the rosemary and drizzle with more olive oil.
Place on the middle oven rack and cook for 10 to 12 minutes. Remove from the oven. Immediately remove the pizza from the pan and cut into rectangles.