Don't even think of attempting this with tinned sweetcorn

This has been working quite nicely recently: Crab & Sweetcorn Chowder.

You will need:
One stick of celery, one onion, one large carrot and one large clove of garlic, all chopped as finely as you can.
Light olive oil, about a tablespoon.
A knob of butter (the only time "knob" is acceptable as a unit of measurement).
Two cobs of sweetcorn, kernels stripped (hold the cob on end and run a sharp knife vertically down it to strip the kernels. Then pick half the little buggers up off the floor and hope no-one noticed).
A heaped dessert spoon of plain flour.
About 300 ml of milk.
250g of small new potatoes cut into 2cm pieces.
One dressed crab (from a proper wet-fish shop or stall, don't bother with supermarket pre-packaged stuff, it tastes of nothing. And if you attempt this with tinned crab meat you'd be better off adding the tin, it'll have more flavour.).
One bunch of flat-leaf parsley, coarsely chopped.

Gently fry the celery, onion and carrot and garlic in the olive oil for as long as you have the patience. Ideally at least half an hour. The vegetables should be frying enough to sizzle quietly, shrink & become soft & translucent but they shouldn't start to brown or char.

Add the butter and when it has melted add the plain flour. Stir & cook the resulting roux for a couple of minutes and then add the milk. Make sure you incorporate all the flour from the bottom of the pan. Heat through until the flour is cooked and the mixture has thickened. You're after a consistency like thin cream so add more milk if necessary.

Add the sweetcorn, potatoes, crab and parsley and simmer gently until the potato is cooked - about half an hour should do. Check the seasoning and add salt. If the chowder is overwhelmingly sweet from the corn keep adding salt until the flavour of the crab starts to come through.

Don't even think of attempting this with tinned sweetcorn