Onion Miso Soup with Rayu Oil Drizzle

Ingredients

• Large sweet onion, 1 thinly sliced
• water, 4 cups
• Miso paste, 3 tablespoons
• Firm tofu, 200g cut into cubes
• Nori seaweed sheet, 1 torn into pieces
• Rayu (Chili Sesame) oil, 2 tablespoons
• Soy sauce, 1 tablespoon
• Mirin, 1 tablespoon
• Vegetable oil, 2 tablespoons
• Salt, to taste