Preheat the oven to 220°C. Whisk 1 tbsp oil and the vinegar in a bowl, add the onion rings and toss to coat. Leave while you prepare the remaining ingredients (the marinade helps to soften the onion and mellows the flavour a little).
Spread the pizza base with the sun-dried tomato paste. Arrange the onion rings and cherry tomatoes on top, then scatter with the sun-dried tomato slices, olives and feta cheese. Drizzle the remaining oil over the pizza.
Bake for 10 minutes or until the base is crisp and the topping lightly browned. Season with ground black pepper. Cut into wedges and serve.