PREHEAT barbecue to medium-high heat. Place tomatoes, cut-sides up, in greased 8-inch square foil pan. Drizzle with dressing; sprinkle evenly with cheeses. Place pan on grate of barbecue; close lid.
GRILL 10 to 12 min. or until cheeses are melted and bottoms of tomatoes are browned.
SPRINKLE with herbs just before serving.