Step 1

Peel and dice (or slice) the onions. Check the Notes below for tips on how to dice them easily.

Step 2

In a large heavy-bottomed pot/skillet, add the oil and heat over medium-high heat.

Step 3

Once hot, add the onions to the pan and cook for 15 minutes, stirring often, until the onions are tender and golden-brown.

Step 4

Reduce the heat to low, add the thyme and bay leaf, and cook for 3-5 minutes.

Step 5

Sprinkle the sugar over the onions, leaving it to cook for 5 minutes, untouched. The aim is for it to melt over the onions without stirring.If you stir the sugar in with the onions, it can seize into clumps. While it’s possible to melt it back down again, the process takes longer.

Step 6

Increase the heat to high and cook for 5 minutes, or until the sugar caramelizes and turns golden-brown, without stirring.To avoid the caramel burning, it's important to watch the pan fairly closely at this point so you can reduce the heat if needed.

Step 7

Add the balsamic vinegar and stir, then simmer on low for 5 minutes. During this time, the balsamic onion jam mixture should thicken, though feel free to simmer it slightly longer if needed.It's ready when you draw your spoon across the bottom of the pan, and it leaves a clear trail for several seconds.

Step 8

Finally, remove the herbs from the pan, taste, and season the sweet onion jam. Allow it to cool before transferring it to a sterile jar to store.

Step 9

Storing: Store the jam in a sterilized jar in the fridge for 7-10 days. Alternatively, transfer it to the freezer for 2-3 months (in a jar with 1-inch headspace or in portions in an ice cube tray).