Mediterranean Chicken Grilled Pizza

4 teaspoons McCormick® Grill Mates® Garlic & Onion Medley Seasoning, divided

1 cup shredded mozzarella cheese

1/2 cup crumbled feta cheese

1/2 teaspoon McCormick® Oregano Leaves

1 pound fresh pizza dough or frozen dough, thawed or 1 prepared thin pizza crust (12-inch)

1 tablespoon olive oil

1 can (8 ounces) tomato sauce

2 plum tomatoes, thinly sliced

1/3 cup sliced black olive s

1/3 cup chopped red onion