Taco Salad

INGREDIENTS

• 4 flour tortillas (8-inch)
• Avocado, peeled, pitted, cut into pieces
• Sour cream
• Shredded cheddar cheese
• Romaine lettuce, torn into pieces
• Salt and freshly ground pepper
• Chopped fresh cilantro
• Juice of 1/2 lime
• Shredded carrots
• Frozen corn kernels, thawed
• Grape tomatoes, cut into halves
• Canned black beans, drained, rinsed
• 1/4 cup red-wine vinegar
• 1 cup olive oil
• 1 pound ground sirloin
• 3/4 teaspoon ground chili powder
• 1 1/2 teaspoons ground cumin
• 2 tablespoons tomato paste
• 1 small onion, chopped
• Sliced scallions