Grilled Chicken Tostadas

Ingredients

• Pickled Onions:
• 4 cups thinly sliced red onion (about 1 large)
• 2 cups boiling water
• 1/2 cup fresh orange juice (about 1 medium orange)
• 1/2 cup red wine vinegar
• 1/8 teaspoon kosher salt
• Chicken:
• 2 garlic cloves, unpeeled
• 1/2 cup fresh orange juice (about 1 medium orange)
• 1/2 cup red wine vinegar
• 2 tablespoons achiote paste, crumbled
• 2 tablespoons fresh lime juice
• 2 teaspoons olive oil
• 1/2 teaspoon kosher salt
• 1/4 teaspoon ground allspice
• 1/4 teaspoon freshly ground black pepper
• 1 1/2 pounds skinless, boneless chicken breasts
• Remaining ingredients:
• Cooking spray
• 12 (6-inch) corn tortillas
• 2 cups shredded leaf lettuce
• 3/4 cup chopped peeled avocado
• 3/4 cup crumbled queso fresco cheese
• Pickled jalapeño pepper slices (optional)
• Reduced-fat sour cream (optional)
• Cilantro leaves (optional)

Preparation

1. 1. To prepare pickled onions, combine onion and 2 cups boiling water in a large bowl. Cover and let stand 15 minutes; drain. Add 1/2 cup orange juice, 1/2 cup vinegar, and 1/8 teaspoon salt to onions. Cover and chill at least 2 hours.
2. 2. To prepare chicken, heat a small nonstick skillet over medium heat. Add garlic to pan; cook 7 minutes or until tender, stirring occasionally. Remove garlic from pan; peel and mash. Combine garlic, 1/2 cup orange juice, and the next 7 ingredients (through pepper) in a large zip-top plastic bag. Seal bag, and shake vigorously to dissolve achiote paste. Place each chicken breast half between 2 sheets of heavy-duty plastic wrap, and pound to 1/2-inch thickness using a meat mallet or small heavy skillet. Add chicken to bag, and seal and marinate in refrigerator for 30 minutes, turning bag occasionally.
3. 3. Prepare grill.
4. 4. Remove chicken from bag; discard marinade. Place chicken on grill rack coated with cooking spray; grill 5 minutes on each side or until done. Let stand 15 minutes. Shred with 2 forks.
5. 5. Lightly coat tortillas on each side with cooking spray. Place tortillas on grill rack; grill 2 minutes on each side or until lightly browned.
6. 6. Arrange 2 tortillas, overlapping halfway, on each of 6 plates. Top each serving with about 1/2 cup chicken mixture and about 1/2 cup pickled onions. Drizzle evenly with vinegar mixture. Top each serving with 1/3 cup lettuce, 2 tablespoons avocado, and 2 tablespoons cheese. Garnish with jalapeños, sour cream, and cilantro, if desired.