Though the Italian Mostarda does contain mustard, it's only distantly related to the yellow stuff in the squeeze bottle.
Rather, it's fruit preserved in syrup that gains quite a kick from a healthy jolt of powdered mustard seed or essence, and is one of the standard condiments served with boiled meats in northern Italy (see the ultimate boiled dinner, fit for a king).
Though you'll find it from Piemonte on through the Veneto and down into Emilia Romagna, the best known variation is that from Cremona, made with whole fruit that acquires a voluptuous firmness during the preparation.
Making Mostarda is quite easy, and it also makes an excellent gift.
2 1/2 pounds (1 k) fruit
1-1/2 pounds (5-700 g) sugar
The juice of an orange
Mustard essence, or powdered mustard and white wine