Flat Iron Steak with Red Wine Sauce

INGREDIENTS

• 2 1/2 cups dry red wine
• 3 tablespoons extra-virgin olive oil, plus extra for garnish
• 6 tablespoons cold unsalted butter
• Salt and freshly ground black pepper
• 1 onion, thinly sliced
• 1/4 cup tomato paste
• 2 (1-pound) flat iron steaks or tri-tip steaks
• 1 teaspoon dried oregano
• 1 tablespoon minced garlic