Without mustard essence, here is a recipe that gets closest to traditional mustard fruits – it's not exactly the same, but still delicious. Serve alongside cured meats or hard, sharp cow's or sheep's milk cheeses.
1kg/2lb fruit of your choice, such as pear, green figs or quince
500g/1lb caster sugar
11/2 tbsp strong mustard seeds
1 tbsp strong mustard powder
250ml/8fl oz white wine
The juice of one orange
Wash and pat dry the fruit, slice in half, remove the skin and cut into small pieces. Put the fruit in a preserving pan (or medium-sized pan with a heavy bottom). Pour the sugar over and add enough water to cover. Boil for 15 minutes, skimming off any white foam that comes to the surface. Cook until large bubbles begin to form and the jam begins to set. Test by placing a spoonful on a cold plate. It should just set but not be too thick.
Warm the mustard seeds gently in a pan until they begin to pop. Grind with a pestle and mortar to a fine paste. Mix with the mustard powder and place in a clean saucepan. Pour over the wine and orange juice and place over a medium heat. Stir to dissolve the powder and reduce by a third. Remove from the heat and spoon over the fruit. Mix well and place in well-sterilised jars. Allow to cool completely and place in the fridge. It will keep well for two weeks.