Roast beef & caramelised onion toasties - Good Food Middle East

Ingredients

• 2 brown onions , finely sliced
• 1 tbsp butter
• 1 tbsp sunflower oil
• 300ml gravy (can be made up using 4 heaped tsp gravy granules)
• 150g roast beef (see tip below)
• 1 tsp English mustard
• 4 slices of crusty bread (we used Lidl wheat and rye)
• 40g Lidl extra mature cheddar , grated
• 20g stilton , crumbled
• ½ tbsp softened butter
• 1 tsp sunflower oil