In a small dry skillet over medium heat, toast the white sesame seeds just until golden and fragrant, about 2 to 3 minutes. Transfer to a small bowl and let cool.
In the same skillet, toast the black sesame seeds for 1 to 2 minutes, stirring constantly. Add to the bowl with the white sesame seeds and let cool.
Add poppy seeds, dried minced garlic, dried minced onion, and flaky sea salt to the bowl. Stir to combine.
Transfer to an airtight jar and store at room temperature for up to 6 months.