Slice the portobello mushrooms, and chop the onion. Saute in olive oil, with a clove of minced garlic, and salt and pepper to taste, until the onion is transparent.
Lay out pitas on a cookie sheet, as the base of the pizzas. Top with pizza sauce. Lay 5-6 fresh basil leaves on top of the sauce.
Top with the sauteed onion and mushroom mixture.
Sprinkle with shredded mozzarella cheese, and crumbled feta.
Broil, until the pizza is heated through, the top is lightly browned and the cheese melts. Cut into quarters with a pizza cutter and serve.