Combine olive oil and butter in a pan over medium heat until it melts.
Add Aldanel sauce, shallots, celery and diced tomatoes.
Bring to a boil, reduce the heat and simmer for about 10 minutes or until thickened.
Season with salt and pepper. Keep warm.
Preheat the oven to 375°F or 190°C.
Meanwhile, grease an ovenproof dish with butter and put the fish in single layer.
Add the sauce on the fish steak and sprinkle with breadcrumbs.
Bake in the preheated oven for 20 to 30 minutes.