Back when I was first teaching myself about preserving and canning, I came across an old method for making strawberry preserves that called for setting the strawberries (tossed with sugar) on a tray out in the sun to cook down slowly and gently over a period of a few days. It sounded intriguing, but for a novice still struggling with the logistics of canning, it also sounded like a lot of extra work.
More recently, I came across a similar recipe in Edon Waycott's excellent book Preserving the Taste (a must-have for serious jam makers). Since canning had become second nature by then, I decided to make the effort and give the sun-cooked method a whirl. Hoo, doggie. Let me just say that sun-cooked strawberry jam is to almost any other strawberry jam what a brand-spanking-new Jaguar convertible is to a 1989 Ford Escort. Tana Butler over at I Heart Small Farms listed it (well, my version, anyway) as one of her Five Things to Eat Before You Die (scroll down).
The beauty of sun-cooking is that it concentrates the fruit very gently, preserving the delicate flavor compounds. What results is about the purest flavor of whatever fruit you subject to the process. It works especially well with something like peaches, which have such a bright flavor and aroma that is so quickly destroyed by cooking. Because the process involves short periods of boiling (for hygienic purposes), there is some degradation of flavor, but nothing like what happens with boiling to the gel-point.
Now that I'm pushing preserves to the public, I'm required to make whatever I make in ridiculous quantities. Last year, I put up 39 jars of Strawberry conserve and sold it all in about 5 weeks. I decided to go huge this year. Well, bigger. There's a pristine organic farm about 40 miles from here (Clear Brook Farm in Shaftsbury, VT) that grows perfect and delicious strawberries. I picked two flats there last year (and then had to fill in with non-organic berries from another farm after the wet weather ruined any berries that weren't being heavily sprayed with fungicide) but determined by the end of the summer that taking the time to pick my own fruit wasn't part of a sound business model. I negotiated a small discount on 8 flats of berries from Clear Brook. 8 flats. 64 quarts. Filled the back of my little car (and filled it with heavenly perfume).
By the time I got home I was down to 63 quarts. To digress slightly about the advantages of organic vs. non-organic farming: I found myself craving strawberries yesterday and stopped in a nearby non-organic farmstand to pick up a quart. They're disgusting. They're sweet and strawberry-flavored but slightly insipid...and have a pronounced chemical aftertaste. Not making this up. I wish I could find the article I read a few years ago, written by a former oncologist who got out of the business after his own cancer; he moved to Vermont and took up organic farming. He maintains that organically grown fruits and vegetables have better flavor because the harder work of growing up without chemical aids causes them to develop stronger flavor compounds. Makes sense to me.
It took my husband and me about 2 and a half hours to hull all the berries. I'd always used the sharp tip of a paring knife to hull strawberries, but somehow had the presence of mind to pick up a couple of strawberry hullers – only 99¢ a piece, but worth their weight in gold. They're not at all the frivolous kitchen gadget I'd always thought they were; they'll hull a berry in about 1/3 of the time it takes to do it with a knife, and leave a lot more of the berry behind.
So, here's the basic method for sun-cooked strawberry conserve:
First, watch the weather carefully to make sure you'll have 3 or 4 days of at least partial bright, hot sunshine. My husband and I are weather junkies and check no fewer than 4 different weather websites several times a day. A good one for long-range forecasts is the Accuweather site (punch in your zip code for your local weather).
You will need some kind of wide, flat vessel in which to “cook” the berries. I use these commercial kitchen trays made by Cambro, but you could also use shallow plastic lidded tubs made by Rubbermaid or Sterilite – from one of the Marts (Wal- or K-) – or even shallow baking sheets (though I'd be afraid aluminum might throw the flavor off). Something with a lid is preferred, as it will save you carting the trays indoors at night to protect them from rain or dew. You'll also need some kind of screening to put over the trays to keep bugs and airborne detritus out; plastic window screening or (my choice) bridal tulle work well. You'll also need a table or bench on which to set the trays of berries, in a spot that gets full sun for most of the day (you could set them on the ground, but crawly things would likely find their way up under the screening).
(NOTE: I've amended the sugar : berry ratio as of 07/17/08; as last year's conserve aged in the jar, I found it became slightly bitter for lacking sugar.)
The formula (which can be expanded endlessly): per quart of fresh berries, you will need 3/4 cup of sugar and 1/2 TBSP of fresh-squeezed lemon juice. If you are accustomed to very sweet jams (inexplicably the fashion these days) you can use as much as a cup of sugar per quart. But I urge you to go light on the sugar the first time round.
Since I use organic berries, I don't wash them first, but if you're using sprayed berries, do give them a light rinse. Pick through the berries and remove the hulls (use a knife if you must, but I heartily recommend a huller!) and discard any very bruised or moldy berries or grass or straw. Toss the hulled berries with the sugar in a non-reactive bowl or tray and leave them to stand overnight at a cool room temperature (mid-60s-ish; if it's going to be warmer than that, put them in the fridge). If you can, stir the mixture a few times to distribute the slowly dissolving sugar.
In the morning (because you want to take full advantage of the day's sunshine), transfer the berries to a pot large enough to accommodate the berries plus some boiling-up expansion. Add the lemon juice and carefully bring the mixture to a boil (start with low heat at first until the whole mix is hot, then goose the heat to almost high). As soon as the mix boils, reduce the heat and simmer enthusiastically for about 5 minutes. This is just to kill off any bacteria or mold spores that may be tempted to grow as your berries languish in the hot sun. You don't want the fruit to get mushy and break apart.
Pour the hot berries into your trays, dividing carefully if using more than one – make sure the syrup:berry ratio is equal for both (or all 4 if you are a nut like me). Place the tray(s) on your bench or table and cover with your mesh of choice, tucking it at the sides so that there are no points of entry for ants, etc. Let the trays bake in the sun all day, but carefully stir them from time to time, or just use a big spoon and ladle the syrup over the top of the berries.
At the end of the day (or any time during it, if rain threatens), cover the trays, or drag them indoors. If critters are a problem (raccoons, bears), you would be wise to bring the trays in. We have bears here; a smart young male plundered my bird feeders two Junes ago.
The other morning, while my berries were out, I was wakened by a loud and paraphernalia-enhanced crash at about 4:30, just as it was starting to get light; I dashed out onto the deck, naked and with my heart in my throat, expecting to see Mr. Black bathing in sweetened strawberries...but all was calm and right. I discovered later that one of the cats had knocked a flower-bucket full of metal plant markers off the potting bench – loud but innocuous.
Let the berries sit out in the sun for 2 or 3 (or even 4) days, bringing them in or covering them at night, until the syrup is thickened,...look for it to wrinkle slightly when pushed with your finger. If the weather doesn't cooperate, a thinner syrup is fine. What you will end up with is plump, whole berries in syrup, thicker or thinner depending on weather conditions.
Once the mixture is suitably concentrated, bring it in and pour it into a large pot. Carefully bring it to a boil (as before) then ladle into clean glass jars and can using whatever method works for you.
We put up 85 jars of strawberry conserve last Friday, and 41 jars of sun-cooked rhubarb jam. This method works for any fruit preserve except for ones that rely on pectin and high heat for jelling. I've used it with great success for raspberry, black raspberry, and apricot preserves, and to high acclaim for peach “butter”.