Greek Pita Pizzas

olive oil, plus more for brushing

(8-inch) pita

red wine vinegar

Salt and pepper

chopped fresh oregano (or ½ tsp. dried)

small red onion, halved and sliced thin

pitted kalamata olives, chopped (or sliced black olives)

grape tomatoes, halved

hummus

shredded mozzarella cheese

crumbled feta

Tzatziki sauce, for serving