Cheese and harissa onion toastie

This recipe has been made by food writer, stylist and cook Rosie Birkett. She has partnered with us to created her favourite ways to cook with Leerdammer. Enjoy!

Makes 1 toastie


  • 2 tbsp olive oil
  • 1 red onion, finely sliced
  • 1 white onion, finely sliced
  • 1 tbsp harissa (I like rose harissa)
  • 1 tbsp mayo
  • 1 clove garlic, minced
  • 2 slices of sourdough
  • 4 slices Leerdammer
  • Knob of butter – 5g
  • Tbsp rapeseed oil


  1. Heat the olive oil over a medium heat. Add both the onions, season well, and cook down for 20-30 mins, until sweet, soft and caramelised. Stir through the harissa paste.
  2. Mix the garlic into the mayo and spread both sides of each slice of bread with the mayo. Top one half with half the onions, followed by 3 slices of the cheese. Top with more onions, and another slice of cheese, then top with the other half of bread.
  3. Heat a skillet over a medium-to high heat and melt a knob of butter and tbsp rapeseed oil. Carefully place the sandwich into the skillet and cook for 3-5 minutes, turning halfway through, until the bread is golden and crisp and the cheese is melting.