Heat oven to 375°F.
Combine half-and-half, poblano, red pepper, onion, garlic and tarragon in medium-size pot. Bring to boiling. Reduce heat; simmer 25 minutes or until vegetables are tender. Pour into blender; add flour and salt. Puree; return to pot. Keep warm.
Rub baking pan large enough to hold fish fillets in single layer with butter. Add wine. Place fish in pan. Sprinkle with salt and pepper. Cover with aluminum foil.
Bake in 375°F oven for 20 minutes or until fish is easily flaked with a fork. Place cooked fish on a bed of cooked yellow rice if you wish. Spoon sauce over top.