Preheat the oven to 375°F (190°C).
Prepare the potato crust by combining grated potatoes, olive oil, and salt in a mixing bowl.
Press the mixture firmly into the bottom and sides of a greased pie pan.
Pre-bake the crust for 20 minutes until slightly golden.
In a mixing bowl, whisk together the eggs, milk, black pepper, and oregano.
Add the crumbled feta and diced tomatoes to the egg mixture and stir to combine.
Pour the filling into the pre-baked potato crust.
Bake for an additional 30-35 minutes, or until the filling is set and lightly browned.
Allow the quiche to cool for 10 minutes before slicing.
Serve warm or at room temperature.