- Infuse the kombu: Add rinsed kombu and water to a small saucepan. Heat gently over medium-low until small bubbles appear (do not boil). Remove kombu and discard or reserve for stock. 
- Add flavor: Stir in grated ginger and mashed umeboshi. Let steep for about 1 minute to infuse warmth and tang. 
- Whisk the matcha: In a separate bowl or mug, sift 1 teaspoon of matcha powder. Add a splash of the hot infusion and whisk vigorously until smooth and frothy. Gradually pour in the rest of the liquid while whisking. 
- Adjust flavor: Add lemon juice for brightness and honey (or maple syrup) to taste. Stir well. 
- Serve: Hot version: Pour into a mug, garnish, and serve immediately.Iced version: Cool slightly, pour over ice, and top with mint or lemon slice.