Ingredients

• 8 (6-inch) flour tortillas
• 1 1/2 pounds skirt steak
• 2 tablespoons canola oil
• Salt and freshly ground black pepper
• 1/2 head romaine lettuce, thinly shredded
• 1 medium red onion, thinly sliced
• 1 ripe avocado, peeled, pitted, halved and diced
• Grilled Tomato Salsa, recipe follows
• 8 ounces sour cream
• 2 tablespoons canola oil, plus more for brushing tomatoes
• 2 serrano chiles
• 1 small red onion, coarsely chopped
• 4 cloves garlic, peeled
• 6 plum tomatoes, halved and seeded
• Salt and freshly ground black pepper
• 2 limes, juiced
• 1/4 cup chopped fresh cilantro leaves