Fish gratin with tomatoes and olive oil

In Andalucia this summer I was staying opposite a bakers, who showed me round his bakery on arrival.  On the floor was a crate of enormous tomatoes that felt hot, soft and heavy in the hand, and reeked of the sun.  I would only really want to do this recipe if I had tomatoes of similar quality.


Fish gratin with tomatoes and olive oil

Spinach (not baby spinach)
Cooked new potaotes
Parsley, finely chopped
White fish, filleted, skinned, boned and cut into 2cm cubes
Milk
Cream
Lemon juice
Flour
Butter
Excellent quality extra virgin olive oil
Large tomatoes, stem attachment removed, sliced into 1cm slices, some of the seeds removed, salted lightly and left to drain on a biscuit cooling rack over your sink's draining area for 20 minutes
Dried red chilli, chopped finely or crushed
White breadcrumbs
Fish stock
Salt and white pepper


To make the fish stock just cover some fish trimmings (not eyes, gills or guts), sliced onion, carrot, celery, fennel or fennel seeds, peppercorns, bay leaf with cold water, bring to a simmer, skim and simmer very gently for 15 minutes.  Allow to cool for 5 minutes then strain through a fine seive/muslin.  This bit is easy, just ask a fishmonger for some trimmings.

Wilt the spinach in some olive oil then place in the base of a large, fairly shallow, buttered gratin dish.  Lay the new potatoes on top, sliced into 1cm rounds.  Sprinkle over the parsley.

Make a white sauce as explained in the macaroni cheese post, using half milk, half slightly reduced fish stock.  Enrich with some cream, season well and sharpen with lemon juice.  To acheive the right thickness it's easier to make more sauce than you need, so start off with a decent amount of butter/flour for the roux.

Pour some sauce over the potatoes then mix more sauce with the fish in a bowl.  This is the next layer of the gratin, and should be fairly liquid.

Lay the tomato slices on top and pat very gently down into the surface, without overlapping them.

Toast the breadcrumbs in a frying pan with olive oil, salt, pepper and some dried chilli.  Cover the tomatoes with a fine and even layer of the chilli breadcrumbs, then drizzle (awful word) some more olive oil on top.

Bake for 40 minutes at 180C.  Serve on its own, followed by a salad.