In a tilt skillet, sauté the onions and garlic in the olive oil until soft and fragrant but not browned. Season with oregano and salt.
Add the tomatoes and cook, stirring often, on high heat in order to extract and reduce as much liquid as possible. Be sure to spread the tomatoes out and not crowd them. This may need to be done in batches.
Combine the olives (if using), eggs, milk, and cheese; add to the pan and cook, stirring often, until the eggs are scrambled and fluffy. Sprinkle with parsley (if using).
Transfer to a perforated hotel pan to drain any excess liquid.
Using a 3-ounce ice cream scoop, load the eggs into the pita pocket and serve.
