How to Make Spicy Italian Mostarda

A Fruit Preserve, Not a Mustard

You may think this is a recipe for Italian mustard due to its name, but, although Italian mostarda does contain mustard, it's only distantly related to the yellow stuff in the squeeze bottle. Instead, it's fruit preserved in syrup that gains quite a kick from a healthy jolt of powdered mustard seed or mustard oil. As such, it's one of the standard condiments served with boiled meats in Northern Italy. Today, it's also often served as an accompaniment to cheeses or charcuterie. 

Though you'll find it from Piemonte on through the Veneto and down into Emilia-Romagna, the best-known mostarda is that from the Lombardy town of Cremona, made with whole fruits that acquire a voluptuous firmness during the preparation.

Mostarda has an unusual flavor: somewhat sweet, because the fruit is candied in sugar syrup, but also spicy, with a powerful, pungent kick from the mustard. It is hot in the way that wasabi and horseradish are spicy: a sort of intense burning in the sinuses.

What You Need

The ingredients to make mostarda are somewhat basic and readily available. To make 1 pint of mostarda, you will need 2 1/2 to 3 pounds assorted fruit, such as apples, pears, kiwi, mango, strawberries, tangerines, cherries, and orange sections, and 1 1/2 pounds granulated sugar. The juice from 1 orange is required, as is 2 ounces of mustard powder; alternatively, you can use 10 to 15 drops of mustard oil. Also, have 1 cup of white wine on hand and one 1-pint-size canning jar.

Prepare the Fruit and Add the Sugar

Peel, seed, stem, and cut up the fruit. Place in a large bowl.

Add the sugar to the fruit. You can increase the amount of sugar if the fruit is not naturally sweet enough, or if you simply want a sweeter mostarda. 

Add the Orange Juice and Rest

Pour the juice of 1 orange over the fruit-sugar mixture and let the fruit rest for 24 hours, gently turning the pieces a couple of times. Purists leave the bowl uncovered, but you may want to partially cover it with a clean kitchen towel. The next day, the sugar will be completely dissolved.

Drain the Fruit

The next day, put a colander in a small pot and empty the bowl of fruit into it. Drain the fruit well and return it to the bowl. 

Concentrate the Syrup

Heat the fruit syrup in the pot over medium heat. Reduce the heat when it comes to a boil and continue simmering it until its volume is reduced by half. Skim the foam from the surface with a slotted spoon or strainer. Pour the syrup back over the fruit and let sit overnight again.

Drain, Concentrate Syrup, and Steep a Second Time

The sugar in the concentrated syrup will extract more moisture from the fruit, which will begin to firm up. You will need to drain and concentrate the syrup a second time by repeating steps 5 and 6.

Steep the fruit in the re-concentrated liquid overnight again. 

If Using Powdered Mustard Seed

The next day, flavor your mostarda. If using mustard powder, dissolve the mustard powder in 1 cup of white wine in a small pot, and gently heat the mixture over low heat. Stir occasionally, and let the mixture bubble for a few minutes.

If Using Mustard Oil

If you are using the mustard oil, drain the fruit into a pot again, and remove about a shot glass's worth of syrup from the pot. Set the pot over low heat.

In the meantime, carefully add 10 to 15 drops of mustard oil to the syrup in the shot glass. (If you get some mustard oil on your skin, wash it off immediately with warm soapy water, as it is a powerful irritant.)

Drain the Fruit and Concentrate Again

 While you are preparing the infusion, drain the fruit and concentrate the syrup once again.

Sterilize Your Canning Jars

While the syrup is concentrating for the fourth time, sterilize your jars.

Put the Fruit in the Jars

Fill the sterilized jars with the fruit. Don't be surprised at how much the fruit has compacted. This recipe should yield one 1-pint jar of mostarda.

Add Powdered Mustard

If you are using powdered mustard, add the infusion and then the hot syrup to cover, tapping the jar to dislodge air bubbles as you fill. ( If you use all of the infusion, the mostarda will be quite strong. Some people enjoy it that way, but feel free to make your first batch a little less spicy if you like.)

Add Mustard Oil

After adding the fruit, if you are using mustard oil, pour in the contents of the shot glass, and then add hot concentrated syrup to cover, tapping the jar repeatedly as you fill to dislodge any air bubbles.

Cover and Seal

Cover the jar with the lid and seal. There's no need to sterilize the mostarda; the sugar concentration is high enough that it will inhibit bacterial activity.

Clean and Store

Wipe the jar clean and store in a cool, dark place. The mostarda will be ready in 2 weeks.

Regional Variations

There are many regional variations of Mostarda in Northern Italy; some derive their sweetness from concentrated grape must, and are opaque. This recipe derives its sweetness from sugar and is translucent.
The best-known mostarda in Italy is Mostarda di Cremona, which is made with a mixture of peeled, cored fruit: apricots, peaches, kiwis (a recent addition), Bartlett pears, small apples, tangerines, cherries, quinces, figs, and so on.

Kitchen Notes

If the fruit is small, the presentation is much nicer if you leave the fruit whole (but peeled, with seeds and stems removed), or at the most cut in half lengthwise. If you use larger fruit, cut it up as necessary.

Also, feel free to use other combinations of fruit than the ones suggested in this recipe. In Mantova, they use peeled, sliced, and cored quinces, and you may find mostarda made with everything from green tomatoes to finely sliced watermelon rind.

In commercially prepared Mostarda di Cremona, the syrup is invariably colorless and crystal-clear, regardless of the fruit that goes into it. This is in part because some of the coloring substances are in the skins, which are removed, and also because cooks are careful not to overheat and thus caramelize the sugar.