PLACE fish on rack of broiler pan sprayed with cooking spray. Mix mustard, 1 Tbsp. dressing and 1/2 tsp. garlic; spread onto fish.
BROIL, 4 inches from heat, 6 to 8 min. or until fish flakes easily with fork. Meanwhile, place beans in medium saucepan; add enough water to completely cover beans. Bring to boil; simmer on medium-low heat 6 min. or until beans are crisp-tender. Drain beans in colander.
ADD remaining dressing and garlic to saucepan; cook on medium heat 1 min., stirring occasionally. Add beans; cook 2 min., stirring occasionally. Top with nuts. Serve with fish.