Empty flour in a large bowl, add the sugar, salt and yeast and mix.
Add the olive oil and mix with a spoon. Now start adding the water mixing until you have a thick dough.
Place the dough and knead for about 5 minutes adding more water or flour as needed until you have dough that is uniform and is not sticking to your hands.
Place the dough in the bowl, cover with plastic wrap, and let it rise in a warm place for about an hour.
Preheat the oven at 350 degrees Fahrenheit (180 Celsius).
When dough is ready, drizzle some oil on the bottom of a round pan that is about 14-15 inches diameter (or you can use smaller and divide into 2 pans). Spread the dough with your hands so it covers the whole pan. Brush again with olive oil.
Chop the onions in medium size pieces and place in bowl, add about a teaspoon of olive oil and add the tomato paste and mix, until all the pieces are covered.
Make little dents in the dough with your fingers and spread the onions.
Cut the tomatoes in thin slices and then cut in half or in quarters depending the size of the tomatoes and place on top of the onions. Drizzle with a bit of olive oil, add freshly ground pepper and a bit of kosher salt.
Bake in the oven for about 50 minutes on the lower rack.