Put flour into a large bowl and make a deep well in the middle. Pour warm water into the well, mix in the yeast, using a bit of flour in the mix. Add the sugar, salt, and flour to the well, let stand for 10 minutes until mixture bubbles. Slowly stir all of the flour into the yeast mixture. When it gets too thick to handle place it on a board and knead it until elastic. Form a ball, place into a greased bowl, then turn it over so the top of the ball is greased. Cover with a towel and let rise in a warm and draft free place for an hour or until double in bulk. Preheat oven to 450 degrees. Punch down dough and divide in half. Refrigerate one half for later. (Allow extra time to rise). Roll the other half into a circle about 38 cm across. Place on a 36 cm greased pizza pan, roll edges to form a rim. Transfer the pie a pizza pan. Bake the pizza until the crust begins to brown, about 6 minutes. Remove from oven and cover with cheese, leaving 1 cm border around the edges. Arrange the salmon and onion on top and drizzle evenly with olive oil. Return to the oven and bake until the crust is golden brown and puffy, the cheese begins to melt and the salmon is heated thru, about 4 minutes. Remove from oven to a cutting tray or board and lightly brush the crust with olive oil. Garnish with dill. Slice and serve immediately.