This red onion jam recipe is simple to make and full of flavor. Use it as a sandwich spread, spoon it over mushrooms on toast, or serve it alongside cheese and crackers for an easy crowd-pleaser.
Welcome to my first post in August. I’ll keep this short — I’m busy planning a road trip that’s just a couple of weeks away. It’s hard to believe summer is already more than half over; the months have flown by.
Although I’m not ready to say goodbye to summer, I’m quietly looking forward to autumn. I love seasonal comforts: chunky knitwear, favourite TV series coming back (Outlander is top of my list), and digging into all the jams I make over the warmer months.
But for now, we’re still in summer — even if the UK weather isn’t behaving — and there’s still time to make more preserves. This recipe is a twist on traditional fruit jams: it uses red onions instead of fruit. If that sounds odd, give it a try — the caramelized sweetness and vinegar balance make a wonderfully versatile condiment.
I prefer red onions for this jam because of their color and slightly sweeter, milder flavor, but white onions will work perfectly well too. When caramelized, all onions develop the deep sweetness that makes this jam so comforting.
This jam is brilliant on toasted sourdough or a soft bloomer loaf. Spread it on bread, top with fried mushrooms, and you have a delicious, rustic snack or appetizer. The combination of sweet onion jam, earthy mushrooms, and good toast makes for a satisfying bite that’s simple to assemble and great for guests.
My love of onions goes back to childhood. I was the kid who would happily tuck into mountains of fried onions with bread — sometimes skipping the sausages entirely. That early fondness stuck with me, and while I don’t eat raw onions like an apple these days, I still reach for them often in the kitchen.
There are many onion jam recipes that call for long, slow cooking, but I prefer a shorter time so the onion keeps a little texture. I cook mine about 25–30 minutes so the onions caramelize but retain slight bite. If you like a softer, more jammy texture, extend the cooking time, but take care not to overcook into a mush. Once cooled, the jam keeps well in the fridge — up to two months when stored in a clean jar — so it’s handy to make a larger batch and enjoy it over time.
That’s all for today. I’ve recently launched a short email series with my favourite food photography tips — more on that in another post — and I have a few more exciting things in the pipeline, so stay tuned.
Until next time!
📖 Recipe
Red Onion Jam (+ mushrooms on toast)
Ingredients
For Red Onion Jam
- 2 large red onions (sliced)
- 1 medium garlic clove (crushed)
- ¼ cup brown sugar
- ⅓ cup red wine vinegar
- 2 tablespoon olive oil
- 1 pinch salt
- 1 pinch black pepper
For Mushrooms on Toast
- 2-4 slices sourdough bread (thick slices work best)
- 100 g mushrooms (chopped or sliced)
- 1-2 tablespoon butter (or vegan spread)
- 10-15 fresh basil leaves (optional)
- 1 pinch salt
- 1 pinch black pepper
Instructions
For Red Onion Jam:
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Heat the olive oil in a large frying pan. Add the sliced onions and crushed garlic. Stir in the brown sugar, a pinch of salt and pepper. Cook over medium heat, stirring occasionally, until the onions are soft and caramelized, about 25–30 minutes.
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Stir in the red wine vinegar and bring to the boil, then simmer for an additional 5–10 minutes. Remove from the heat and allow to cool slightly.
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Transfer to a clean jar once cooled and refrigerate. The jam will keep for up to two months.
For Mushrooms on Toast with Red Onion Jam:
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Melt the butter or vegan spread in a frying pan and add the mushrooms. Season with salt and pepper and fry for about 5 minutes until golden and tender.
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Meanwhile, toast the bread under a grill or in a toaster until crisp.
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Spread a generous layer of red onion jam on each slice, top with the cooked mushrooms and finish with fresh basil leaves if using. Serve immediately.
Note: Recipes are developed and tested using metric measurements. For the most accurate results use digital scales. Conversions to US customary units are provided but may not have been tested.