Heat a dry skillet over medium heat. Add the white and black sesame seeds. Toast them for about 3 to 5 minutes, stirring often, until they are lightly golden. Remove from heat and let cool.
In a bowl, combine the cooled toasted sesame seeds with the dried onion flakes, dried garlic granules, poppy seeds, and flaky sea salt. Stir well until evenly mixed. Transfer the seasoning to an airtight jar for storage.