Preserving Summer's Bounty with Slow-Roasted Tomatoes



A couple of years ago I wrote a post on how to make tomato sauce with fresh summer tomatoes. Every year I make as much sauce as I can and put it in my freezer to use during the autumn and winter months (in baked pasta, braises, etc.). But sauce is only one way to preserve the delicious vine-ripened tomatoes of summer. Another great way is to dry them out a bit by roasting them in a slow oven. The resulting tomatoes are a fraction of their original size and have an intense, concentrated flavor. Tucked away in the freezer, they can be used all through the tomato-less months of winter on pizzas, in pasta sauces, relishes, soups, stews, vegetable gratins and ... that is, if you don't eat them all before winter arrives. They are that good.

I have been slow-roasting (or "oven-drying") tomatoes for as long as I have been cooking professionally. Besides being a great way to preserve tomatoes, the slow roasting process creates a product that packs a powerful tomato flavor punch without adding a lot of bulk or liquid to a dish. Moreover, if your tomatoes aren't great, slow-roasting them will bring out the very best flavor possible, making it a very useful technique.

You don't really need a recipe to slow-roast tomatoes. The peeled tomato halves are simply dressed with olive oil, salt, pepper and optional herbs and garlic and baked at a low temperature until they have shrunk and given up a large percentage of their liquid. Depending on your oven, the temperature you choose to use, the juiciness and size of the tomatoes you are roasting, the number of tomatoes you are roasting and finally just how dry you want your tomatoes to be (some chefs prefer them a bit softer and less shriveled than others), the process can take anywhere from an hour and a half to three hours...even longer. This is a perfect activity for a day (or evening) whey you will be home doing other things and can check on the tomatoes occasionally.

The recipe I am posting is largely taken from Tom Colicchio's book Think Like a Chef. The main difference between his recipe and any other recipe I have ever seen is that instead of going to the trouble to blanch and shock the tomatoes in order to peel them, he starts them out in a hot oven. This causes the skin to release itself from the flesh of the tomatoes so that it can be easily pulled off and discarded. (A brilliantly efficient method.) The oven temperature is then reduced so the tomatoes can have a nice slow roast.

Another great thing about Colicchio's recipe is that it produces more than just roasted tomato halves. One of the by-products of his process is soft, sweet roasted garlic.  The roasted cloves can be peeled and used in innumerable ways. The other "extra" is the flavorful tomato liquid that is poured off during the roasting process. This roasted tomato juice can be added to soups, sauces, vegetable ragouts, vinaigrettes, etc. I love it that there is no waste. Like the tomatoes, both the juices and the roasted garlic can be frozen.

The finished products: tomato halves, roasted garlic cloves, roasted tomato juice

I have changed only a few details of Colicchio's recipe. First, after I peel the skins away, I brush the surfaces of the tomatoes with some of the oily tomato juices released during the initial high temperature roast. I also wait until the tomatoes have been peeled before I salt & pepper them. It doesn't make sense to me to salt the skins which will then be discarded. If it bothers you that there is no salt underneath the tomatoes, go ahead and salt them when you toss them with the olive oil and then give them a very light sprinkle of salt after the skins have been removed. Finally, I remove the garlic cloves from the pan when they are just soft—after about an hour. If they remain in the pan for the entire time, they darken too much for my taste and they also tend to become a bit hard.

You should not feel like the quantities given in the recipe below are iron-clad in any way. It is the process—not the amounts—that is important. I have simply recorded the quantities of ingredients I used the last time I roasted a batch of tomatoes. You should roast whatever you have on hand. For whatever quantity of tomatoes you decide to roast, just remember to choose a rimmed pan that is just the right size to hold all of the tomato halves in an even single layer. If the pan isn't full, the tomatoes will roast unevenly.

In the coming months, I will try to remember to occasionally post recipes that make use of these delicious tomatoes. But if you make them I'm sure you will have no trouble coming up with your own uses...layered into a summer lasagne, tucked into a sandwich, made into a quick relish to top a goat/ricotta smeared crostini..... If you want to have some left for the winter, you should probably make a really big batch.

Slow-Roasted Tomatoes

3 to 3 1/2 lbs. vine ripened tomatoes, cored and halved cross-wise (if using plum tomatoes, halve them length-wise)
3 or 4 sprigs winter savory
8 to 10 sprigs thyme
1 head of garlic, cloves separated and left unpeeled
1/4 c. olive oil

Place the tomato halves in a large bowl with the remaining ingredients and toss to coat everything with the oil and distribute the garlic and herbs uniformly.

Transfer the tomatoes, herbs, garlic and all liquid to a rimmed half sheet pan that has been lined with parchment paper.  (If you don't have any parchment paper, simply brush the pan with a thin film of olive oil. )  The tomatoes should be placed cut side down and should be arranged so that they are evenly spaced.  The garlic and herbs too, should be distributed evenly around the baking sheet. 

Place the tomatoes in a hot oven (375° to 400°) and roast until the skins split and begin to separate from the flesh—about 20 to 25 minutes. Remove the pan from the oven and tip off the accumulated juices into a heat-proof container. With the assistance of a pair of tongs or a small paring knife, lift off and discard the skins. Brush the peeled surface of the tomatoes with some of the olive oil that has risen to the top of the tomato juice that was just poured off. Season the tomatoes lightly with salt and pepper (be careful—the tomatoes are going to shrink considerably).

Reduce the oven temperature to 275° to 300° and return the tomatoes to the oven.  The lower the temperature, the longer the tomatoes will take...but the less likely they might become over-caramelized as they roast. At the higher temperature, they will cook more quickly, but you will need to monitor them more closely and possibly reduce the temperature as the tomatoes near doneness.

The tomatoes will take anywhere from another 1 1/2 to 4 hours to finish. Remove the garlic cloves after an hour of roasting time (or whenever they have become soft and tender) and continue to tip off and reserve any accumulated juices from the pan as necessary. The tomatoes are done when they have shrunk and appear concentrated—but they should not be dried out.

Allow the tomatoes to cool on the sheet before lifting off and transferring to storage containers. Store the tomatoes in between layers of parchment paper in an airtight container. They will keep in the refrigerator for about a week. If frozen, they are best used within 6 months.

(Recipe adapted from Think Like a Chef by Tom Colicchio)