Simple Udon Noodle Soup (Kake Udon)

Ingredients

• 10g Kombu (dried kelp)
• 15g Katsuobushi (bonito flakes)
• 10g Niboshi (dried sardines)
• 1l Water
• 5 tbsp (75ml) Soy sauce
• 2 tbsp Mirin
• 1/2 tsp Salt
• 4-5 portions Udon noodles
• Spring onion finely chopped
• Toppings of your choice