Step 1

Heat the oven to 350°. Put the taco shells on a baking sheet and bake them until crisp, about 8 minutes. Break each one in half.

Step 2

In a medium saucepan, heat 1 tablespoon of the oil over moderate heat. Add the beans, salsa, and 1/4 teaspoon of the salt. Cook, mashing with a potato masher, for about 5 minutes.

Step 3

In a small glass or stainless-steel bowl, whisk together the vinegar, mustard, pepper, chili powder, and the remaining 1/2 teaspoon salt. Add the remaining 4 1/2 tablespoons oil, whisking. Add the cilantro.

Step 4

To serve, spread one side of the taco-shell halves with the refried beans and put four on each plate. Top with layers of the lettuce, tomatoes, avocado, cheese, chicken, and olives. Pour the dressing over the salads.