Start with the sauce: sweat some shallot and a garlic clove in butter. Add 1/3 bottle of light red wine, some vegetal stock, tomato puree, salt, pepper and some herbs (rosemary, sage, laurel, parsley). When thickened use a sieve to get the solid parts out. Then whisk in some butter to get a velvety sauce. Set aside to warm later.
Turn on the oven at 180 C.
Slice the white of a leek lengthwise, then cut into half rings. Sweat the leek in butter. In the meantime mix flour, salt and peper in a plastic bag. Put in two nice cod filets and shake. Fry the fish in butter and olive oil, about 3 mins each side.  Then put the pan in the oven for another 5 mins. Slice some more white of the leek very thinly. Heat some archaide oil in a saucepan and deep fry the leek.
Serve as shown.