This North African-style sauce is also delicious spooned over yogurt or eggs for breakfast, or simply tossed with any roasted vegetable for a flavor-packed side.
Preheat oven to 375 degrees. Roast hazelnuts on a baking sheet until fragrant and skins loosen, about 10 minutes. Let cool briefly, then rub off skins with a clean kitchen towel (do not worry about getting them all, just what comes off easily). Let cool completely.
In a small skillet over medium-high, toast cumin and coriander seeds until dark brown and fragrant, about 3 minutes. Finely grind in a spice grinder, or crush with a mortar and pestle.
Pulse hazelnuts in a food processor until texture resembles coarse meal. Add spices, cilantro, zest, garlic, and 1 teaspoon salt; pulse to combine. Add oil and orange juice; pulse to combine. Chermoula can be refrigerated in an airtight container up to 1 week.