Portobello & blue cheese melts - Good Food Middle East

Ingredients

• 1 red onion, cut into wedges
• 1 tsp olive oil
• 2 tbsp balsamic vinegar
• 2 Portobello or flat mushrooms
• 1 tsp thyme leaves
• 25g blue cheese
• 1 ciabatta bread roll
• handful rocket leaves
• oven fries, to serve (optional)