Coffee Braised Roast W Caramelized Onions Serrano Gravy

Name: Coffee-Braised Roast W/ Caramelized Onions & Serrano Gravy
Ingredients: 4 lbs beef top round roast, trimmed of fat; 1⁄2 teaspoon coarse sea salt; 1⁄4 teaspoon fresh fresh coarse ground black pepper; 4 teaspoons olive oil, divided; 2 large onions, halved and thinly sliced (4 cups); 4 serrano peppers, whole, seeds removed; 4 garlic cloves, minced; 1 tablespoon fresh thyme, chopped; 1⁄2 cup strong brewed coffee; 2 tablespoons red wine vinegar; 2 tablespoons cornstarch; 2 tablespoons water