Method

• 1.
  Heat 1 tablespoon oil in a frypan over low heat. Add the onion and cook, stirring, for 10-12 minutes until soft. Add the sugar and balsamic vinegar, then cook, stirring, for a further 5 minutes or until the onion is caramelised. Remove the pan from the heat and set aside.

• 2.
  In a separate frypan, heat the butter and the remaining 1 tablespoon oil over medium heat. Add the garlic, mushroom and thyme, then cook, stirring, for 3-4 minutes until soft. Remove the pan from the heat and set aside.
• 3.
  Heat a chargrill pan or large non-stick frypan over high heat. Add 1 tortilla and cook on one side for 30 seconds or until slightly toasted and charred. Remove from the pan, then repeat with the remaining tortillas.
• 4.
  Place 4 tortillas, toasted-side up, on a benchtop. Top each one with a quarter of the caramelised onion, mushroom mixture, grated cheese and rocket leaves, then sandwich with the remaining tortillas, toasted-side down.
• 5.
  Return the chargrill pan or frypan to high heat. Add 1 quesadilla and cook for 2-3 minutes until toasted on one side. Carefully flip, then cook for a further 1-2 minutes until the cheese is melted and the tortilla is toasted. Keep warm while you repeat with the remaining 3 quesadillas.
• 6.
  Meanwhile, to make the lemon sour cream, combine the sour cream and lemon juice in a bowl.
• 7.
  Serve the warm quesadillas with a dollop of lemon sour cream.