Fish in Monk's Clothing

"Merry Christmas! Could you come to the kitchen and help with the fish?" It wasn't exactly unexpected, but it was still a nice little challenge, like Top Chef the home edition. Unfamiliar kitchen, lots of competition for space, no specific instructions and the opportunity to make or break someone's Christmas dinner. On such occasions, it's good to have a little bit of wisdom from Julia Child in your back pocket.

My travel plans to Illinois had been delayed for two days by snow and ice, so I ended up flying on Christmas day, getting to my brother's house about an hour and a half before guests were showing up for dinner. Everything on the menu was traditional in that household except for the fish, which my brother doesn't eat, so I got volunteered to cook that.

Again, I did have some warning. Several days before, my brother had mentioned on the phone that some guests had asked for fish instead of tenderloin, and that he had bought some frozen tilapia filets. All he needed was a recipe. I said that for simple white fish, I used to like the method that Julia Child had gotten from some monks in the south of France, an episode entitled ``Fish in Monk's Clothing,'' where the fish is baked covered in lots of aromatic vegetables. "Search on the internet, I'm sure you'll find a recipe," I said.

Well, he had searched and had found four recipes for tilapia, but none were Julia's. I didn't like the look of them and although I hadn't made this dish in years, I preferred to find my own way again. Fortunately, the dish turned out well, but the down side was that I had no recipe to give to the people who asked for one, only a bunch of vague constraints.

The essential thing is that the mix of vegetables should taste good, but be reasonably mild so as not to overpower the fish, and should still have a lot of moisture in it. You need enough to cover the fish reasonably well. The vegetables drip flavor into the fish while at the same time protecting it from losing moisture in the direct heat of the oven.

(For the Haskell readers, think of the following as a sort of QuickCheck test suite for the actual method.)

1. Chop and saute a bunch of aromatic vegetables, season with salt and pepper, thyme or other mild herbs, and reduce with some white wine. The vegetables should be soft, but still very moist and it's good to have some liquid remaining.
   
2. TASTE the vegetables. If they don't taste good, fiddle with the seasoning until they do.
   
3. Season the filets with salt and pepper, then place on an oiled baking pan. If the tails of the filets are much thinner than the main part of the body, overlap them so that the fish is roughly the same thickness all over.
4. Layer the vegetables over the fish along with any remaining liquid.
5. Bake gently until the fish is just opaque and flakes easily. I think we did 350F for about 15 minutes, but this will vary with the amount and size. You could also microwave it for 5-10 minutes, covered, if you use a glass or porcelain casserole dish.
   

As for which vegetables, that varies based on what I have on hand, but start by sweating an onion in olive oil and butter, then adding celery and a few chopped cloves of garlic. It is fine to brown the onion a bit, but not the garlic. This time we added some chopped mushrooms and parsley. I have added carrots in the past, but that's about as strong as I would go. Julia Child used a head of iceberg lettuce chopped up, but I've never had the nerve to try that. Spinach or swiss chard make a nice choice, but kale, mustard greens and cabbage are too strong. Fennel is a nice addition if you like anise flavor.

Any simple white fish works here, such as flounder, sole, tilapia, catfish, etc. I think I've done it successfully with bluefish, but I would avoid salmon.

How close this is to what Julia Child did, I really don't remember, because I only saw the show once long ago, but I'm pretty sure I've got the essence right. It's a simple way to marry fish with whatever vegetables are available. In any case, it was good enough for Christmas dinner.

The Pattern of Walking

These images may look like Christmas lights, but they were created simply by holding a camera on long exposure while walking on the beach at dusk. If you just wave the camera around, the patterns are uninteresting, because they have little cohesion, but just walking straight created unexpectedly interesting results.

They remind me of high school physics, when we learned about cycloids by attaching a light to a bicycle tire. The walking images are more regular than I expected, but also far more convoluted than a cycloid. Just as the hidden motion of the tire was revealed in that experiment, these images must show something fundamental about walking. I'm just not sure what.

Never turn your back on the ocean

That's a good rule in SCUBA diving and it's a good idea on the beach.

Functional Programming and the Universe

In Lee Smolin's TED talk How science is like democracy, he describes how our understanding of space and time has evolved. He describes three stages of cosmology:

1. Aristotelian, which is hierarchical and all properties are defined with respect to that hierarchy;
2. Newtonian, where properties are all defined with respect to an eternal absolute background of space and time;
3. Quantum Theory or Relational Universe, where the universe is nothing but an ever evolving network of relationships, and all properties are about relations between subsystems.
   

Two quotes from the talk that jumped out at me:

According to Newton, space is just the way that god knows where everything is.

And this one, regarding the modern relational model of the universe:

Space is just one aspect, so there's no meaning to say absolutely where something is, there's only where it is relative to everything else that is, so we call it a relational universe.

In other words, even the physicists don't use an object-oriented model to describe objects any more.

Halloween Slideshow

As a public service, I've made a Halloween slideshow out of photos I've taken over the last year. Comprising over a hundred scary, ghoulish and horrifying images, you can set it playing on a spare monitor and be frightened all day long.

Pie Night

My friends Michael and Susan have a wonderful tradition that grew out of growing too many pumpkins.

Pie night.








They make 10-15 pies, everybody brings a pie, everybody eats pie until they can't eat no more.


And then we have pie for breakfast.

Two-dimensional zip

I've been doing battle with things like CSS recently (the W3C will be first against the wall when the revolution comes,) so it was a pleasure to run into a little Haskell puzzle and an elegant solution.

I was working with a matrix represented with a list of lists: [[a]]. I wanted to add the row and column indices to each element, giving: [[((Integer,Integer),a)]].

This isn't a pattern I remember seeing before, but it seemed simple enough, so I just hacked away. Here's my first try:

> index grid = zipWith indexrow [0..] grid
>     where indexrow rn rs = zipWith (\cn r -> ((rn,cn),r)) [0..] rs

Serviceable, but neither pretty nor general. The one dimensional case is so elegant; for any list, you can add indices with:

> index1d xs = zip [0..] xs

The zip function is simple and the infinite list of indices covers all cases. So it occurred to me I was looking for two things: a two-dimensional version of zip; and a grid of index tuples, semi-infinite in both directions.

Both turned out to be simple enough. Here's the grid of tuples using list comprehensions:

> indices2d = [[(r,c) | c <- [0..]] | r <- [0..]]

And the two-dimensional zip:

> zip2d = zipWith zip

And it's easy to reproduce the "With" version:

> zip2dWith f = zipWith (zipWith f)

So now my function looks like this:

> index2d grid = zip2d indices2d grid

or just:

> index2d' = zip2d indices2d

This version is clearer, simpler and easily generalizable to higher dimensions.