Preheat oven to 450°.
Place focaccia halves, cut sides up, on a baking sheet. Combine minced garlic, tomato paste, and dried oregano in a small bowl; spread evenly over focaccia halves. Top evenly with roasted peppers, onion, and capers; sprinkle with feta cheese. Bake at 450° for 12 minutes or until focaccia is golden. Cut each pizza in half.
Bottled roasted red bell peppers taste delicious. They are often less expensive than fresh peppers, and they help to slash prep time. The feta cheese will not melt, so use the crust's golden color as an indicator of doneness.