Japanese vegetable stir-fried noodles (Yasai yaki soba)

INGREDIENTS

• 100ml/3½fl oz ready-made teriyaki sauce
• 4½ tbsp ready-made crushed yellow bean sauce
• 1 lemongrass
• 1 tbsp freshly grated root ginger
• 200g/7oz soba noodles
• 2 free-range eggs
• ½ green pepper
• ½ red pepper
• 1 onion
• 8 spring onions
• 10 mushrooms
• 2 garlic cloves
• handful fresh bean sprouts
• 4 tbsp ready-made teriyaki sauce
• 3 tbsp vegetable oil
• ½ tsp sesame seeds