- Prepare the salsa: In a bowl, whisk together the lime zest, lime juice, garlic, salt and pepper. Slowly whisk in the olive oil.
- Transfer 3 tablespoons of the vinaigrette to a large bowl and add the beans, corn, tomatoes and chilies; mix gently. Reserve the remaining vinaigrette. Let the salsa stand for at least 10 minutes until the flavors have blended.
- Assemble the salads: Add the lettuce to the reserved vinaigrette and toss to coat. Divide the tostadas and lettuce among 4 plates. Spoon the salsa over the lettuce, top with the chicken and serve immediately.