Rub chicken evenly with 1/2 the fajita seasoning. Heat the oil in a skillet over medium heat, and cook the chicken 8 minutes on each side, or until juices run clear; set aside.
In a large saucepan, mix beans, corn, salsa and other 1/2 of fajita seasoning. Heat over medium heat until warm.
Prepare the salad by tossing the greens, onion and tomato. Top salad with chicken and dress with the bean and corn mixture.
