Preheat oven to 450 degrees F.
Combine the extra virgin olive oil, minced garlic, oregano, and optional red pepper flakes in a bowl and set aside.
Drizzle extra virgin olive oil on the bottom of a sheet pan. Knead the dough to cover most of the pan.
Once the dough is kneaded and spread to cover most of the sheet pan, use a spoon to evenly distribute and spread the olive oil and garlic mixture on top of the dough.
*Very importantly, once the tomatoes are sliced, shake out the juice (some seeds might come out too) from the tomato slices and evenly place them on the dough. This will prevent a soggy crust.
If using red onion, take the thinly sliced red onions and evenly distribute them on top of the dough.
Bake the pizza in a preheated 450-degree oven for about 10-12 minutes or until the dough is golden brown.
Remove the pizza from the oven and sprinkle the mozzarella on top. Return to the oven for only 2-3 minutes or until the cheese is melted.