HEAT oven to 350ºF.
PLACE half each of the onions, peppers and tomatoes in 13x9-inch baking dish sprayed with cooking spray; sprinkle with 1 Tbsp. cilantro.
TOP with fish; sprinkle with paprika. Cover with remaining onions, peppers and tomatoes. Drizzle with dressing; top with 1 Tbsp. of the remaining cilantro and potatoes. Top with cheese; cover.
BAKE 1 hour or until potatoes are tender, uncovering for the last 10 min. Sprinkle with remaining cilantro.