Preheat oven to 375˚F (190˚C). Not necessary if you cut the chicken breasts in half.
Coat both sides of the chicken breasts with Cajun seasoning. In an oiled cast-iron skillet, cook chicken on medium-high heat 4 minutes per side, or until chicken is browned.
Bake for 15-20 minutes, or until the internal temperature of the chicken reaches 165˚F (72˚C). Let the chicken rest for several minutes.
In a small bowl, combine yogurt, minced garlic, lime juice, olive oil and reserved seasoning mixture. Set aside. Cut chicken into pieces.
In a large bowl, add lettuce, chicken, red onion, avocado, cherry tomatoes, and black beans. Add dressing and toss.