1. In a heavy-bottomed saucepan, melt butter over medium-low heat.
2. Add the onions and fry until translucent, about 25 minutes. 
3. Add the vinegar, honey, salt, and pepper. Stir and cook, covered, about 30 minutes, stirring occasionally. 
4. Add apples and cook for another 30 minutes. 
5. Transfer confit into sterilized Mason jars, filling them 1 cm (1/2 inch) from the top. Seal and sterilize. 

Chef’s secret

This recipe's acidity level means it can be canned using the boiling water technique.

• Sterilize jars by immersing in boiling water for about 5 minutes. The lids must be new to ensure a proper seal. Soak lids in hot water before using.
• Fill jars, leaving a headspace of about 1 cm (½ in.).
• Place lids and screw bands on jars but do not over-tighten.
• Immerse jars in boiling water and boil for at least 15 minutes.
• Remove jars from water and let rest for 24 hours. The lids will be depressed and make a sudden popping noise when the seal is tight.
• The jars can be stored for one year in a dark, dry, cool place.

Nutrition tip

This onion confit is delicious on burgers, meat paninis, in pasta, or served with grilled meat or cheese and crackers.