Veggie burgers

Ingredients

• 100g cashew nuts
• 1 tbsp olive oil
• 1 red onion, chopped
• 1 carrot, grated
• ½ small leek, chopped
• 100g mushrooms, sliced
• 1 clove garlic, crushed
• ¼ tsp thyme leaves only
• 100g cooked brown rice
• 1 tbsp soy sauce
• 40g gruyere cheese, grated
• 50g breadcrumbs
• 1 tbsp honey
• 1 egg yolk
• Flour, for dusting
• 2 tbsp sunflower oil, for frying
• Mayonnaise, to serve