Chop all veggies thin and cut fish to 1 1/2 inch cubes. Heat oil and butter in large stick-free pan, adding herbs and spices to top. cook lightly then add stock and bring to a boil. Add fish to boiling liquid and cover. Cook 15 mins on 'simmer'. Remove fish and strain veggies. Serve veggies to side of fish. Add cornstarch to liquid and bring to boil. Let it thicken and pour over fish. Add lemon juice and parsley for looks.