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10 ultimate sandwich recipes

Whether as part of a picnic spread or a quick grab-and-go lunch, the sandwich is a real British classic that's definitely worth celebrating. From traditional flavour combos to exotic twists, our favourite recipes show just how versatile and delicious the humble sarnie can be.

French onion toasties
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French onion toasties

These classic toasties are inspired by the flavours of French onion soup – the delicious caramelised onions giving added oh là là! With a melting mozzarella and Gruyère centre and pan-fried in butter for a crisp finish, this is a cut above your usual sandwich!

  1. Melt 20g butter and oil in a lidded frying pan over a medium-high heat. Add the frozen onions, cover and defrost for 5 mins.
  2. Once defrosted, uncover and cook on high for 3-5 mins until most of the liquid has evaporated. Reduce the heat to low, add the salt and half the thyme leaves; cover and cook for 35-40 mins until caramelised. Add the brandy (or balsamic vinegar or white wine), increase the heat to medium; cook for 3 mins. Season; add splashes of Worcestershire sauce, if you like. Transfer to a plate; wipe the pan with kitchen paper.
  3. Divide the onions between 2 slices of the sourdough. Top with the mozzarella, Gruyère and the remaining thyme leaves; sandwich with the other 2 slices of bread. Melt the remaining 30g butter in the pan over a medium heat, add the sandwiches; cover and cook for 3-4 mins. Flip and cook for 3 mins more.

Tip: The onions take a while to caramelise – double up and freeze for future use, or swap for 200g Tesco Finest red onion chutney.

Freezing and defrosting guidelines

Freeze caramelised onions only. In order to enjoy optimum flavour and quality, frozen items are best used within 3 months of their freezing date. For more tips on freezing and defrosting food, read our article Love Your Freezer.

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View full recipe details
  • Ingredients
  • 50g butter​
  • 1 tbsp olive oil
  • 500g pack frozen sliced red onions
  • pinch of salt
  • 6 thyme sprigs, leaves picked
  • 1 tbsp brandy, balsamic vinegar or white wine
  • a few splashes of Worcestershire sauce
  • 4 slices Tesco Finest white sourdough
  • 100g reduced-fat mozzarella, torn
  • 80g Tesco Finest Gruyère, sliced