Combine first 4 ingredients in a large bowl; toss and let stand 3 minutes. Remove chicken from marinade; discard marinade. Sprinkle chicken evenly with 1/4 tsp salt.
Heat a grill pan over medium-high heat. Coat pan with cooking spray. Add chicken to pan and cook 6 minutes on each side or until done.
To prepare salsa, combine tomato & next 4 ingredients (thru pepper) & remaining 1/4 tsp salt in a medium bowl. Add avocado; stir gently to combine. Serve salsa over chicken.