In a small bowl, dissolve the yeast and sugar in warm water. Let it sit for 5-10 minutes, or until frothy.
In a large bowl, mix the flour and salt. Make a well in the center and pour in the yeast mixture and olive oil.
Stir until a dough forms. Turn the dough out onto a floured surface and knead for about 5 minutes, or until smooth and elastic.
Place the dough in a lightly oiled bowl, cover with a damp cloth, and let it rise in a warm place for 1-2 hours, or until doubled in size.
While the dough is rising, heat olive oil in a skillet over medium heat. Add the onions and cook slowly, stirring occasionally, for 15-20 minutes until they are caramelized and soft.
Add the garlic and cook for another 1-2 minutes. Remove from heat and set aside.
Preheat your oven to 425°F (220°C). Punch down the risen dough and transfer it to a lightly floured surface. Roll out the dough into a rectangular or oval shape, about 1/2 inch thick.
Transfer the rolled-out dough to a baking sheet lined with parchment paper.
Spread the caramelized onions evenly over the dough. Scatter the black olives and chopped anchovies over the onions. Sprinkle with fresh thyme leaves and season with salt and black pepper.
Bake the pissaladière in the preheated oven for 20-25 minutes, or until the crust is golden brown and the toppings are nicely browned.
Let the pissaladière cool slightly before slicing. Serve warm or at room temperature.
Enjoy your meal!