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 

Preparation

Preheat oven to 350 degrees. Lightly brush tortillas with 4 tablespoons oil. Sprinkle with salt and pepper.

Press one of the tortillas into the ovenproof bowl. Bake 13 minutes; an adult should transfer shell to a rack to cool. Repeat with remaining tortillas.

Meanwhile, make beef filling: In a mixing bowl, combine beef with tomato paste, chili powder, cumin, and onion; season with salt and pepper. An adult should heat 2 tablespoons oil in a large skillet over medium heat, add beef mixture, and cook, breaking up meat with a spoon, 10 minutes. Transfer to a bowl; set aside.

Make dressing: In a jar, shake together vinegar, 1/2 cup oil, lime juice, and salt and pepper.

Using a box grater, shred cheese and carrots. An adult can prepare the other toppings, including corn: Heat 2 tablespoons oil in a medium skillet over medium high heat; add 10-ounce package frozen corn. Saute 3 minutes.

Divide beef filling among shells; add toppings and dressing.