Heat a small frying pan over a medium heat.
Add 2 tablespoons of whole black peppercorns and 1 tablespoon of whole coriander seeds to the dry pan.
Toast, shaking the pan frequently, until the spices are fragrant and a shade darker, about 2–3 minutes.
Immediately transfer the toasted spices to a plate and leave them to cool.
Grind the cooled peppercorns and coriander seeds coarsely in a spice grinder or pop them into a resealable bag and crush with a rolling pin.
In a small bowl, mix the ground spices with 1 tablespoon of garlic powder, 1 tablespoon of onion powder, 1 teaspoon of dried dill weed, 1 teaspoon of chilli flakes and 3 tablespoons of coarse sea salt.
Stir until everything is evenly combined and there are no lumps.
Transfer the seasoning blend to an airtight container and store in a cool, dark cupboard for up to 6 months.