To make the dough, combine the water and yeast - cover and allow it to activate-about 10 mins. Add the olive oil, salt and stir to combine.
Begin by adding 2 cups of flour and mixing thoroughly and then slowly adding the last cup until you have an elastic, pliable dough. If you find it is still too sticky try adding a few tbsps of olive oil.
Knead the dough for about 5-6 mins applying lot of elbow grease. Lay the dough on your pre-oiled baking dish and proceed to stretch it out ensuring it reaches the edges of your baking dish.
Cover the dough in cling wrap and with a kitchen towel and leave it to rise in a warm place for about 45 mins-1 hour.
Once the dough has doubled in size, combine your heirloom tomatoes, onions, olive oil, salt and pepper in a bowl and spread this mix evenly over the dough.
Top with generous amounts of Greek oregano and bake in pre heated 200 deg C oven for about 40-50 mins.
Cut up into pieces and serve warm or at room temperature.