Heat a small sauté pan over medium-high heat. Add the coriander and cumin seeds and toast, swirling the pan constantly, until the seeds give off a rich aroma, about 1 minute. Immediately transfer the seeds to a cool plate and allow to cool for a few minutes.

Transfer the seeds to a mortar and pestle or a spice grinder. Add the chili powder, onion and garlic powder, oregano, salt, and pepper. Grind the spices to an even texture. The rub is ready to use now, or you can transfer it to a jar, cover it tightly, and keep it in a cool, dry cupboard or pantry for up to 1 month.