HEAT dressing in medium saucepan on medium heat. Add onions; cook and stir 4 min. or until crisp-tender. Add garlic; cook and stir 1 min.
STIR in next 4 ingredients. Bring to boil; simmer on medium-low heat 5 min.
ADD fish; simmer 5 min. or until fish flakes easily with fork. Serve topped with cheese.