Toast hazelnuts in a dry skillet over medium heat until browned and fragrant. If the hazelnuts still have skins, rub them gently in a dishtowl to remove most of the skins. Use a mortar and pestle (or spice grinder) to pound the nuts into a coarse powder. Pour the ground nuts into a small bowl.
Add the sesame seeds to the dry skillet and toast over medium heat until golden. Add to the ground nuts.
Add the coriander, cumin, fennel, and thyme to the dry skillet and again toast over medium heat until fragrant. Use a mortar and pestle (or spice grinder) to pound the spices into an even, coarse powder. Pour into the bowl with the sesame seeds and hazelnuts. Add salt and pepper and stir to combine.
Serve with a bowl of olive oil and bread for dipping.
Store in an airtight container in the refrigerator (this will help retain the flavor) for several weeks.