Add the white and black sesame seeds to a small skillet over medium heat. Toast for 2-3 minutes while stirring frequently until lightly browned and fragrant. Immediately remove from heat and set aside to cool.

Using a mortar and pestle or small grinder, coarsely grind the toasted sesame seeds, dried yuzu peel, sansho peppercorns, and nori seaweed flakes one ingredient at a time.

Transfer to a small bowl. Add the ground ginger, red chili flakes, and poppy seeds. Whisk ingredients together until thoroughly combined.

Transfer homemade shichimi powder to an airtight container like a jar or spice bottle. Store in a cool, dark place for up to 1 month.