Preheat grill or oven to about 400 degrees F. Ensure cedar planks have been soaked. In large glass baking dish, mix olive oil, minced garlic, fresh dill, lemon zest, and salt together until combined. Add in salmon filets and toss well to coat salmon evenly. Allow salmon to marinate while grill heats.

Place marinated salmon on soaked planks, skin side down. Transfer planks of salmon to grill and cook for 10 to 15 minutes, or until done to your liking. Remove from grill and squeeze remaining zested lemons over fish just before serving.