Pour ½ tsp toasted sesame oil into a cold pan and add 1 clove grated garlic and ¼ tsp grated ginger root. Heat on low to bloom the aromatics, when it starts to sizzle, mix for 30-45 seconds.
Add 500 ml water, and bring to a boil. Lower to a simmer and add 1 tsp sake, ½ tbsp Chinese-style chicken bouillon powder, ¼ tsp dashi granules, ⅛ tsp oyster sauce and ¼ tsp Japanese soy sauce (koikuchi shoyu). Mix until the granules have dissolved.
Add 3 g dried wakame seaweed and mix until it expands. Add 30 g Japanese leek (naganegi) and simmer for about 30 seconds, then turn off the heat.
Taste test, if it's too salty you can dilute it with water. If it's too bland, season with a pinch of salt. Then drizzle with 1 tsp toasted sesame oil.
Divide into serving bowls and top with some toasted white sesame seeds and ground white pepper to taste. Enjoy!
Notes
Chicken bouillon powder varies by brand. My brand is 1 tsp per 200 ml, so if yours is more concentrated (e.g., 1 tsp per 300 ml), use less to avoid oversalting.Use a narrow pot (16-18cm/6-7 inches) rather than a wide one as we only use 500ml of liquid.Measure dried wakame carefully (3g per 500ml). It expands 10x its dry volume, so what looks sparse becomes abundant.Bouillon and dashi brands vary dramatically in saltiness. Always taste-test before serving.For a spicy variation, swap the finishing sesame oil for chili oil (rayu). For brightness, add a few drops of rice vinegar to your bowl. For Korean-inspired depth, stir in a spoonful of kimchi with its juice.Serving ideas:Yakiniku Don, Cold Tofu (Hiyayakko), Japanese Grilled Salmon, Pork Shogayaki (Ginger Pork)